Strategic Assessment

Introduction

The rise of the Islamic State (ISIS) in Iraq and Syria in 2014 and its announcement of the establishment of a caliphate in the Middle East led the United States back to long-term military involvement in Iraq and Syria. Two Presidents implemented the US efforts to eradicate the global threat from the Islamic State: Democratic President Barack Obama (2014-2017) and Republican President Donald Trump (2017-2020). Even though the two Presidents came from opposite political camps, both publicly emphasized their desire to avoid a large-scale deployment of the US military in foreign countries; change the previous policy of intervention in foreign conflicts; and minimize the United States' role as the world's policeman (Dreazen, 2017; Galeotti, 2016; Lubold, 2014). The US military strategy in Iraq and Syria during 2014-2020 included three main components: ground forces; various levels of support for local forces, which focused on training programs and armament; and air strikes—at first independently and then as part of the international coalition.

Barack Obama’s response to the Islamic State was guided by clear and orderly principles, whereby he tried to take action to block the organization's rapid advance and eradicate its influence throughout Syria and Iraq. Obama's military strategy was based on three main principles: refrain from deploying ground combat forces to deal with the problem of the Islamic State; support a combat strategy via local proxy forces ("by, with, and through"); and establish a broad international framework for conducting air strikes against Islamic State targets on the ground. Obama's three principles aimed to reduce contact between US soldiers and actual combat, as well as to avoid public criticism regarding the return to direct military involvement. This was true especially for Iraq, where the United States had been militarily, diplomatically, and politically entangled for eight years, between 2003 and 2011.

Throughout his term, Obama worked to preserve the principles that he initially defined. The international coalition took shape within weeks, and air strikes conducted in this framework succeeded in slowing the advance of the Islamic State and provided significant cover for local forces in ground battles. The aid programs for local forces, which focused on training and the supply of weapons, started tentatively and encountered many obstacles before they stabilized and began to produce results. The aid program in Iraq did not succeed in its first few months in training more than a few thousand fighters, and the program in Syria was closed three months after it was launched due to more serious difficulties in the training process. Toward the end of Obama's term, the program in Iraq succeeded in recruiting additional fighters (even though the number of trainees was still dozens of percentage points lower than initial Defense Department estimates regarding the number of recruits), and the program in Syria was restored in a new and more limited format.

Obama's desire to avoid deploying ground forces in combat areas was the most challenging issue for him throughout the campaign against the Islamic State. During his term, he approved the dispatch of about 5,000 soldiers to Iraq and about 400 soldiers to Syria (Agerholm, 2016; Stewart, 2015). Although his administration emphasized that the soldiers' missions did not include direct combat roles on the ground and therefore the principle that Obama established was not violated, the significant increase in the number of US soldiers physically located on the ground in Iraq, along with the publication of photos of soldiers at the center of the combat area in Syria, led to complaints and criticism toward Obama.

Overall, it can be argued that the combat principles laid down by Obama in Iraq and Syria were identical, but their implementation was different. The differences were also reflected in the dimensions of time and depth; ןn Iraq the scope of the air strikes, the scope of the aid to Iraqi and Kurdish forces, and the number of the ground forces were much higher than in Syria. While the first American soldiers were sent to Iraq as early as June 2014, the presence of American soldiers in Syria began only in October 2015. The difference in the intensity and the effectiveness of the campaign stemmed in part from the belief among the United States and its allies that the fast elimination of the Islamic State in Syria would strengthen the Assad regime—a result that they resisted at that time (Dekel, 2015). The training programs in Syria and in Iraq also started at the same time, but the number of soldiers trained, the scope of the program, and the level financial aid and supply of armaments were larger in Iraq.

While Obama entered the campaign against the Islamic State with principles defined in advance, the principles of his successor, who entered the White House in January 2017, were less clear. Trump sought to win quick achievements in the foreign arena, which would help justify his election and prove his ability to successfully end military campaigns that Obama had failed to end. Luckily for Trump, as he entered the White House the campaign that he inherited reached a point of some stability and even experienced a change in momentum.  All that was left for Trump was to confidently lead the campaign, which was based primarily on Obama's military principles, to the finish line.

Obama's desire to avoid deploying ground forces in combat areas was the most challenging issue for him throughout the campaign against the Islamic State.

In order to speed up the process, Trump took two important steps: he authorized the commanders of the military to make decisions more independently, which led to more soldiers entering the combat area; and he decided to directly arm the Kurdish forces (YPG) in Syria so that they would be able to capture territories from the Islamic State—a decision that Obama resisted (Gordon & Schmitt, 2017). Obama did grant ongoing support to the Syrian Democratic Forces (SDF), (1) but refrained from demonstrating clear public support for the YPG militia in light of its ties with the Kurdistan Workers' Party (PKK), which was recognized as a terrorist organization by the European Union and Turkey (Sloat, 2019).

Unlike Obama, Trump did not attribute special significance to the concept of "ground military forces." Like his predecessor, he promised reduced involvement of US soldiers in foreign conflicts, but never sought to refrain from sending additional ground forces into the combat area, as long as their aim was to accelerate the campaign to eliminate the Islamic State. In an effort to retain the element of surprise against the Islamic State, and possibly also in order to avoid public criticism, starting in March 2017, Trump prohibited publicizing the number of soldiers sent to Iraq and Syria (Hennigan, 2017).

The training programs in Iraq and Syria continued to exist in the same format during Trump's term, and he even extended the program in Iraq for an additional two years, until the end of 2019. In contrast, his relations with the Kurdish forces in Syria, specifically surrounding the issue of armament, were less consistent. The aim of Trump's decision to arm the Kurdish forces was to accelerate the victory of the rebels in the city of a-Raqqah and to restore their control of the largest and most important stronghold of the Islamic State in Syria. After the objective was achieved and in light of mounting pressure from Turkey, Trump decided to change his policy. He ended the armament program, announced the immediate withdrawal of US soldiers from Syria, and appeased the Turks by granting them the mandate to fight against the remaining Islamic State operatives in the border region, where Kurdish forces routinely operated (Borger & McKernan, 2019).

Trump's entry into the framework of the international coalition began smoothly after this mechanism was organized well and operated continuously during Obama's presidency. However, over time his desire to make decisions independently affected the United States' cooperation with the members of the coalition. The decision to withdraw all American forces from Syria at the end of the main combat operations, even though it was not fully implemented, surprised senior members of the US administration, as well as members of the coalition, who were in the midst of discussions on renewed commitments to the Syrian arena (Brookings Institution, 2019).

The Military Presence on the Ground

The Obama Years

After many years of fighting, in 2011 Obama fulfilled his promises to take the last US soldiers out of Iraq (Shanker, 2008). The decision to withdraw the forces signaled the beginning of a new strategy on future American involvement in foreign countries, which was formed in order to avoid as much as possible prolonged involvements that constitute an economic, political, and human burden on the United States. When the threat from ISIS in Iraq and Syria grew in the spring and summer of 2013, Obama's new military strategy shaped and demarcated the characteristics of the American response to the terrorist organization.

In his first references to ISIS, Obama claimed that a policy that includes military intervention on the ground in any country is naive and not realistic. While Obama emphasized that limited military operations and defensive actions would take place to rescue American civilians and protect their security, he claimed that any further US involvement in the region would only consist of assistance to Iraqi forces (White House, 2014). It quickly became clear that the Iraqi army and government were not skilled and strong enough to be an effective counterforce to ISIS. The unwillingness of the Shiite units in the Iraqi army that were positioned in the northeast of the country and their preference for abandoning the battlefield instead of fighting against ISIS (Yadlin, 2015) led to the Obama administration's understanding that it had to invest additional efforts if it wished to prevent the fall of Iraq.

From June 2014 until the end of his term, Obama gradually sent about 5,500 soldiers to Iraq, and starting in October 2015, about 200 soldiers to Syria (Figures 1 and 2) (Agerholm, 2016; Stewart, 2015). The difference between the number of soldiers in the two countries reflected Obama's unwillingness to cooperate with the Syrian regime, the impact of the civil war in Syria on the situation on the ground, and the need to protect American facilities and civilians stationed in Iraq. Until the ground forces entered Syria, American aid was centered around air strikes as part of the global coalition and providing assistance to the moderate rebel forces. Despite the gradual rise in the number of troops, on several occasions Obama emphasized that the role of most of the soldiers was not to fight the Islamic State directly on the battleground but to assist and advise the local forces (Baker et al., 2015; DeYoung & Gearan, 2014). Only in a few cases did the administration admit that US soldiers were sent to Iraq or to Syria in order to conduct military operations or to be directly involved in fighting.

Figure 1: Ground forces in Iraq and Syria, according to Defense Department figures, 2014-2016

Source: DMDC, n.d.

Figure 2: Soldiers in Iraq and Syria (army, navy, air force), according to Defense Department figures, 2014-2016

Source: DMDC, n.d.

The first soldiers sent to Iraq in June 2014 were intended to provide defense for American facilities and civilians, and to transmit intelligence information to Washington about developments on the ground (after the withdrawal from Iraq in 2011, only private military forces operated there). While Obama declared that the forces could be involved in individual operations against Islamic State operatives, it is likely that this possibility was brought up as part of the defense missions and not as a proactive military operation against a predetermined target.

Toward the end of 2015 a special force of 200 soldiers was sent to launch independent raids in Syria and Iraq to capture Islamic State leaders (Stewart & Torbati, 2015). The announcement on sending an operational force designated for hunting terrorist operatives reopened the public debate surrounding the concept of a boots on the ground and Obama's promises.

In an interview given about a month later, Obama emphasized that when he said that there would be no soldiers in ground combat positions, he assumed that the American public understood that he meant that the United States would not enter large-scale military involvement as occurred in Iraq in 2003, but there was no intention to completely refrain from sending ground forces to execute defined military operations (Zenko, 2015). John Kirby, then-press secretary of the Ministry of Defense, echoed Obama's sentiments and claimed that when they talk about forces, they mean a large conventional force of field soldiers that is meant to plan, coordinate, and lead combat operations on the ground (“State Department,” 2016). In the Syrian arena, in late 2015 Obama sent 50 special operations forces to coordinate between rebel groups and the coalition forces. The Secretary of Defense at the time, Ashton Carter, declared that given an operational opportunity, the forces would be ready to conduct ground raids on an individual basis even without cooperating with local forces (Mohammed et al., 2015). In 2016 Obama announced the dispatch of up to 400 additional soldiers to Syria, but emphasized that the soldiers would not operate at the front lines of the fighting and their official roles were described as trainers, advisors, and bomb-neutralization experts. As the fighting continued, Obama's principles and his reluctance to approve massive reinforcement of the ground forces before entering decisive battles in key cities in Iraq evoked frustration among the military's commanders (Rogin, 2016), given the need to take apart and rebuild units in order to meet the military needs with a limited number of soldiers. As a result, Obama was forced to make some changes to enable the continuity of the combat efforts.

One of these changes was sending Joint Terminal Attack Controllers (JTACs) to the battlefield in Iraq after the start of the battle for Mosul in the middle of October 2016, in order to direct the air strikes from the ground. Sending soldiers to the front lines was a significant change for Obama, who until then was unwilling to deploy, or at least to admit to deploying, American soldiers in combat areas.

The majority of the political-media debate surrounding the issue of boots on the ground and whether Obama broke or kept his promises not to deploy ground military forces in Syria and Iraq, mainly revolved around the question of definition: was it about the number of forces physically located on the ground, or about the nature of the forces' role? Quantitatively, the numbers quickly climbed within two years to over 5,500 soldiers in Iraq and about 200 soldiers in Syria. The numbers published officially in Defense Department reports did not match the Pentagon’s public statements or media reports that were attributed to anonymous senior officials in the military, which led to a non-uniform picture of the number of ground forces in Syria and Iraq. In terms of the nature of the forces, despite Obama's insistence that the vast majority of the soldiers stationed in Iraq were not involved in combat roles, and the ambiguous announcements on the objective of the special forces soldiers in Syria, photos published in May 2016 that showed American soldiers operating close to the main combat areas in Syria undermined Obama's firm statements that the American forces were only acting in supporting functions.  (McLeary, 2016).

The Trump Years

During the presidential race, Trump already had strong opinions about the right strategy, as he saw it, against the Islamic State in Syria and Iraq. Despite refusing to reveal its details, claiming the need to retain the element of surprise against the enemy, Trump declared in March 2016 that the United States must increase the number of soldiers on the ground if it wants to bring about the elimination of the Islamic State. Trump claimed that in accordance with what he had heard from senior military commanders, about 20,000 to 30,000 soldiers on the ground were needed to carry out the mission (Gaouette & Starr, 2016).

While Trump talked about significantly increasing the number of soldiers, his election platform was largely characterized by isolationism. His desire to refrain from involvement in "endless wars" (“Transcript,” 2016) and to invest more attention and money in the United States domestic arena led him to criticize sharply the return to military involvement in Iraq and Syria during Obama's presidency. In the past Trump had also frequently criticized the decision to withdraw from Iraq back in 2011, a decision that he believed left the United States without significant military achievements and enabled the rise of the Islamic State.

During his first few months in the White House, Trump took two main actions regarding the ongoing fighting in Syria and Iraq: he asked the military commanders to prepare a new plan within thirty days to defeat the Islamic State, and at the same time granted them broader powers to make tactical decisions in the combat areas. Inter alia, Trump granted Secretary of Defense Jim Mattis the authority to adjust the number of soldiers on the ground (Baldor, 2017).  

In March 2017, after the military sent reinforcements that included Marines to operate artillery in Syria and a paratrooper force in Iraq, Trump ordered a stop to publicizing the number of American forces and their objectives (Hennigan, 2017). As a result, starting in October 2017, the Defense Department also stopped publicizing the number of military soldiers stationed in Iraq and Syria as part of its quarterly reports. The gag order, which was imposed as part of the Trump administration's desire to maintain ambiguity in its military actions, enabled sending additional soldiers without being subject to public criticism. From the information that was published until the end of October, it appears that the number of forces sent to Iraq and Syria expanded significantly in the first year of Trump's term. As shown by Figures 3 and 4, between early 2017 and October of that year, about 2,000 soldiers were added in Iraq and about 1,300 in Syria—an increase of about 33 and 750 percent, respectively.

Figure 3. Number of soldiers (army) in Iraq and Syria, according to Defense Department figures, 2016-2017

Source: DMDC, n.d.

Figure 4: Number of soldiers (army, navy, air force) in Iraq and Syria, according to Defense Department figures, 2016-2017

Source: DMDC, n.d.

Between December 2017, when the government of Iraq declared victory over the Islamic State, and December 2018, when Trump declared victory over the Islamic State in Syria after the liberation of a-Raqqah (the declaration of victory by the Kurdish forces in Syria was only in March 2019, after Islamic State forces were removed from their last stronghold in Baghuz), the Trump administration continued its policy of ambiguity and provided only few updates on the number of US forces on the ground. With the declaration of victory over the Islamic State in Syria, Trump added that he intended to remove all the American soldiers from the country's territory within 30 days. This decision was made even though the Kurdish forces were still fighting Islamic State operatives, and the Pentagon estimated that the caliphate in Syria still had about 14,500 active fighters (Borger, 2018). In a tweet posted the day after the decision, Trump justified the departure of the forces by his desire to protect the soldiers and the  American money (Trump, 2018a).

Trump's announcement on the withdrawal of the forces left many senior administration officials outside of the decision making circle. The commander of CENTCOM at the time, Joseph Votel, admitted that the President did not consult with him regarding the decision to remove the forces from Syria (Youssef, 2019). Secretary Mattis, and later also the envoy to the international coalition, Brett McGurk, submitted their resignations in light of the surprising and fast change in American policy. Even though Trump moderated his statements after the initial announcement and declared that the gradual departure of the American forces from Syria would be slower (Trump, 2018b), the new plan published two months afterwards included leaving only 400 soldiers—a number that was further reduced prior to the Turkish invasion of the border towns in northeastern Syria in October 2019. 

While Obama was forced to contend with the Islamic State when it was at the peak of its power in Syria and Iraq, Trump entered the presidency once the organization was already significantly weakened.

The issue of the US withdrawal was also complicated in the Iraqi arena. Following the declaration of victory, the Iraqi government claimed that the US forces would begin to withdraw as early as February 2018. While the US administration refused to confirm whether a withdrawal of forces had begun or to what extent (Chmaytelli, 2018), it became clear that despite the Iraqi government's desire for the departure of the American forces, Trump was not eager to leave the situation on the ground only in its care, especially in light of the increased activity of Shiite militias in the region. Despite the increased tensions between Trump and the Iraqi government, the US withdrawal from Iraq only began in the second half of 2020. Kenneth McKenzie, then-commander of CENTCOM, claimed that the motive for withdrawing about half of the American forces from Iraq was the US administration's confidence in the Iraqi army's ability to deal with what remained of the Islamic State threat (Shinkman, 2020), but it is possible that a main motive for pulling the soldiers out was to win political points prior to the presidential election in November.

While Obama was forced to contend with the Islamic State when it was at the peak of its power in Syria and Iraq, Trump entered the presidency once the organization was already significantly weakened and the main momentum of the fighting was in the hands of the coalition and the local forces. In Iraq a long battle over Mosul was underway, and in Syria the forces prepared for the battle over a-Raqqah, the largest and most important city in the Islamic State caliphate. Trump's choice of strategic ambiguity makes it difficult to conduct a quantitative comparison with the number of soldiers sent during Obama's term, but the Pentagon's public declarations on deploying soldiers that operated conventional weapons shortly after his inauguration and the gag order on the number of soldiers stationed in Iraq and Syria, could indicate a change from Obama's policy in both the number of forces and their objectives.

Clearly, the issue of boots on the ground in Iraq and Syria was seen completely differently by the two Presidents. At a very early stage Obama promised not to deploy ground military forces in Iraq and Syria, and during his term he continued to justify the decision. Even though he sent enough soldiers, especially in combat support roles, to block the advance of the Islamic State and enable the local forces to crystallize into an organized campaign, he did not fully commit to US involvement on the ground and did not send many ground soldiers on a level that would have ended the war more quickly.

In contrast, Trump was not preoccupied with the semantics of “boots on the ground,” and did not impose declared limitations on the number of forces that were sent into the field or their objectives. As a result, he had the ability to operate with greater freedom in making decisions in the military sphere. His decision to grant broader powers to the Defense Department and to the fighting forces led to an increase in the number of soldiers in Iraq and especially in Syria in a way that enabled, in combination with several other factors, the almost complete elimination of the Islamic State from the region.

Support for the Local Forces

The Obama Years

Establishing relations with the local forces and supporting them in leading the military efforts on the ground was one of the main principles that Obama defined as part of his military strategy in Syria and Iraq. Cooperation with the Iraqi army and the Kurdish forces in Iraq as well as cooperation with the moderate rebel forces in Syria constituted, in Obama's view, the best alternative to direct military involvement by the US military. The Train and Equip Program that operated in Iraq and Syria included a training framework for the local forces and the supply of equipment, weapons, and intelligence information. During Obama's term, both the training program in Syria and the program in Iraq encountered serious difficulties.

A previous training program in Iraq between 2003 and 2011 trained tens of thousands of army soldiers at a cost of $25 billion. Obama decided to reestablish the training framework even after the personnel trained in that program did not succeed in blocking the advance of the Islamic State and even fled the battlefield despite a clear numerical advantage, leaving behind American weapons that fell into the hands of the Islamic State (Kam, 2014). Starting in January 2015, US soldiers (and subsequently also soldiers from the international coalition) began to train Kurdish forces and soldiers from the Iraqi army. The aim of the program was to train about 5,000 soldiers every six weeks and reach a total of 30,000 trained Kurdish and Iraqi soldiers in one year.

In practice, the training program encountered many difficulties: low morale among the soldiers after the victories by the Islamic State; corruption and division within the ranks of the army; the lack of commitment of the army's leadership to send soldiers to training; difficulty recruiting new soldiers; the preoccupation of soldiers already serving with battles in the field; and the American demand to conduct a vetting process for all of the soldiers in training in order to ensure that they were not connected to terrorist organizations and were not charged with crimes in the past. All these led to a situation where in the first three months, only 60 percent of the expected number of soldiers came to train (Lynch III, 2015). Despite the difficulties, Obama decided to persist with the program out of a belief that even if a long time were needed to reach the objective, leadership by local forces was the best way to protect achievements and ultimately to produce stability in the long term. Even though ultimately the training program did not meet its original objective, by early 2017 there was a significant increase in the number of trained soldiers, which, according to official statements, amounted to 37,000 soldiers in the Iraqi defense forces and in the Kurdish Peshmerga (Baron, 2017).

From April 2015 and together with the international coalition, the United States, in addition to the training program, armed Kurdish forces in Iraq with heavy weapons such as anti-tank weapons, rockets, and APCs. Weapons were funded as part of a $2.6 billion aid package that the United States and other countries provided to Iraq starting in 2014 (Robson, 2016).

In January 2015, after Congress approved a $500 million budget, the Obama administration announced its intention to send over 400 soldiers to arm and train moderate Syrian rebels. The aim of the program was to train over 5,000 recruits in the first year, following the Pentagon's estimates that about 15,000 trained Syrian rebels would be needed to recapture territories in eastern Syria from the Islamic State.

As with the training program in Iraq, the program in Syria encountered three prominent obstacles from the start: the break-up of the rebel group Hazm, (2) which was supported by the United States, about two months after the start of the program; the difficulty locating groups of moderate enough rebels who could be trusted; and the prolonged vetting processes that were conducted for new candidates, as with the program in Iraq. Due to these difficulties, the United States succeeded in training only 60 rebels by July 2017. The small number of trained soldiers compared to the large budget allocated to the program led to criticism from Congress regarding the American strategy in Syria and to the program’s closure in October, after only 150 rebels had been trained.

After closing the training program, the American strategy in Syria relied on air strikes, a few dozen special forces soldiers, and covert assistance to units of the Free Syrian Army (FSA) (Black, 2015). Following increased momentum in the fighting against the Islamic State in the second quarter of 2016, the Pentagon restored the training program in a new configuration, which focused on training dozens of select soldiers from each group of rebels and not training entire groups of rebels.

The Trump Years

The training program in Iraq continued to operate during Trump's term, including after the end of the main campaign against the Islamic State in late 2017. Five thousand US soldiers were kept in place to lead the program in order to maintain the soldiers' fitness against Islamic State operatives and to assist the Iraqi government in implementing stronger and more effective governance. In a March 2017 meeting with President Trump, Iraqi Prime Minister Haider al-Abadi expressed his desire to receive American support and further training for the Iraqi defense forces. Following this, Congress approved the continuation of the training program until December 31, 2019.

The good relations between Iraq and the United States during Obama's term deteriorated at the end of 2018 and continued to be tense throughout 2019 and early 2020. This was due to the Iraqi government's desire for a quick withdrawal of the US forces, in contrast with Trump's desire to maintain and even increase the military force in the country in order to prevent Iranian entrenchment (Shavit & Schwartz, 2017). These tensions led to the end of the training program in January 2020.

While the training and armament programs in Iraq continued in an orderly manner in 2017-2018, the situation in Syria was much more volatile. In order to expedite the start of the battle for a-Raqqah, which remained the principal populated city in Syria controlled by the Islamic State, the Pentagon asked the administration to arm the Kurdish forces (Blinken, 2017). In early May 2017, the Trump administration accepted this request and announced the beginning of supplying armaments to the YPG militia. The decision was a significant change from Obama's hesitant policy and his desire to avoid harming diplomatic relations with Turkey. 

While the new aid to the Kurdish forces facilitated the liberation of a-Raqqah in late October 2017, it also led, as expected, to tensions with the Turkish government. In November, after the victory for a-Raqqah, the Turkish side stated that Trump had ordered the administration to stop arming the Kurdish forces in Syria. The administration did not contradict the Turkish declaration and claimed the next day that as part of the transition to the stage of establishing stability in Syria, changes and adjustments in the American support for the forces on the ground would be made (Fraser & Lederman, 2017). Trump's decision to stop arming the Kurdish forces came as a surprise to the Pentagon and the State Department, which were not informed of the abrupt policy change (Fraser & Lederman, 2017).

The cessation of support for the Kurdish forces continued into 2018 with Trump's announcement of the withdrawal of the 2,000 American soldiers from Syria. Without US support and while preparing for an attack by the Turkish army in the border region, the Kurdish forces declared they were suspending all their operations against the Islamic State in eastern Syria (Chulov, 2018). Even though Trump changed his position and slowed the US departure from Syria, he did not retract his renunciation of the Kurdish forces. In October 2019, the Turkish government claimed that Trump had entrusted it with waging the campaign against the remaining Islamic State operatives, and that it was advancing preparations for a military operation in northern Syria, in an area where many Kurdish forces were located. In response to the declaration of the Turkish operation, Trump ordered the withdrawal of about 150 soldiers from northern Syria, in order to avoid the possibility of being asked to intervene in the growing conflict between the Kurdish forces and the Turkish army (Barnes & Schmitt, 2019).

In summary, on the issue of aid for local forces, Obama was guided by clear predetermined principles that he labored to maintain despite the appearance of difficulties at the initial stages of implementation. Even though the training programs did not begin smoothly in Iraq or in Syria, the administration's strategy, based on fighting "by, with, and through," prevented their dissolution. The persistence in implementing these programs started to show results mainly in Iraq, in which about 37,000 soldiers were trained and operated in the field when the fighting's momentum shifted away from the Islamic State. In the Syrian arena, in light of Obama's unwillingness to enter a confrontation with Turkey, the issue of armament continued to lack a real solution.

While Obama operated according to an organized plan, Trump's conduct was pragmatic and fluid. The training programs in Syria and Iraq stabilized to some extent when Trump began his term as President, and therefore there was no motive for far-reaching changes in this particular aspect of the US strategy. In contrast, Trump broke with Obama's policy in Syria in deciding to arm the Kurdish militias directly. After the mission was completed and the Islamic State was pushed out of the most important city that it held, Trump made another policy change, removed the support for the Kurdish forces, and enabled the Turks to pursue their interests at the expense of the most important US ally in the fighting in Syria.  

Air Strikes and the International Coalition

The Obama Years

The use of air strikes was one of the most important measures in Obama's strategy against the Islamic State. Early in the campaign, air strikes were intended to slow the advance of the Islamic State and neutralize the threat that it posed to American interests in the region. After the establishment of the international coalition, the strikes became more frequent and enabled blocking the spread of the Islamic State in Syria and Iraq by striking main centers of operation.

The first air strikes conducted in Iraq by the US Air Force began in August 2014. The strikes were limited in scope and their main objectives were protecting the US consulate in the city of Erbil, the Yazidi minority group that was besieged on Sinjar Mountain, and important civilian infrastructure captured by the Islamic State, such as the Mosul Dam.

While Obama operated according to an organized plan, Trump's conduct was pragmatic and fluid.

As early as the first few months after the rise of the Islamic State, Obama worked to establish an international coalition, partly to ease the burden of the fighting on the United States and to prevent the possibility that the United States would find itself once again entering long-term involvement in a foreign country almost alone. Obama believed in establishing an international framework that would receive broad support and legitimacy and in the long term, have greater chances of succeeding both militarily and politically. In September 2014, several countries from the Middle East joined the coalition, including Egypt, Jordan, Lebanon, and the Gulf countries, and that same month the United States and the coalition forces launched the first strikes in Syrian territory while focusing their efforts on striking operatives, command and control centers, storage sites, and financial centers.

After Obama presented the idea of the international coalition on the UN stage at the end of September, follow-up diplomatic efforts by special envoy to the coalition John Allen (and other senior administration officials who visited many countries) led to more than 40 countries joining within only two weeks, and a total of 83 countries and organizations that took part in the coalition by the end of its operation in 2020. Only a few countries actively participated in the air strikes, while more countries helped train the local forces, contributed to the supply of equipment and ammunition, and provided financial aid (Eran & Barak, 2016). During Obama's term until January 2017, the international coalition led by the United States conducted 10,741 air strikes in Iraq and 6,278 air strikes in Syria (Figures 5 and 6).

Figure 5: Increase in the number of air strikes in Syria and Iraq under Obama, 2014-2016

Source: Airwars, 2018

Figure 6: Number of air strikes by month during Obama's term, 2014-2016

Source: Airwars, 2018

While the strikes in Iraq and Syria in the first few months succeeded in slowing, albeit partially, the Islamic State's takeover of additional cities in Iraq and Syria, the strategy of relying mainly on air strikes was not problem-free. The ability of the coalition's forces to conduct fast air strikes and to enable a constant presence of warplanes over the combat areas was limited, as without operation centers in Syria and Iraq, the aircraft had to take off from airfields in more distant countries such as Kuwait, Greece, Jordan, and Turkey.

Another problem was the risk to civilians. As the fighting took place mainly in urban areas, the lack of reliable intelligence information from the ground made it difficult to locate high quality targets which caused civilian casualties (Levenson, 2021; Philipps et al., 2021). This problem was partially solved only toward the end of 2016, when JTACs were sent into the combat areas in order to direct the air strikes accurately. Due to the difficulties of fighting in urban areas, by late 2016 coalition aircraft struck mostly economic infrastructure held by the Islamic State, although often those sites played a dual role and in tandem served the basic needs of the local population, such as the supply of electricity, food, and water (Dekel, 2014).

The Trump Years

While the United States continued to lead the coalition's operations during Trump's term, it seems that his preference for making decisions alone or in a small circle affected the perception of the US commitment to the coalition and to the idea of multilateral cooperation in fighting the Islamic State. The most prominent obstacle was Trump's decision to change the policy in Syria and to pull 2,000 soldiers out of the field at the end of 2018. This decision was taken several days after special envoy to the coalition Brett McGurk and Secretary of Defense Mattis presented their future plan in Syria to the members of the coalition, in order to recruit renewed commitments from the rest of the countries. The decision sparked a crisis of confidence between the US administration and the coalition, as well as between Trump and McGurk, who resigned in protest of the policy change (Brookings Institution, 2019).

Even before the emergence of the crisis between the United States and the coalition, during the second half of 2016 and the first ten months of 2017, the coalition moved the focus of the strikes to Syria, and thus helped the rebel forces in the prolonged battle for a-Raqqah. As charted in Figures 7 and 8, the number of strikes in Syria rose significantly between May and October 2017 and reached about 1,400 strikes in August. Reports by organizations and the media about many civilian casualties, along with an increasing number of strikes each month, indicated that Trump had adopted a looser policy than that of his predecessor regarding opening fire and air strikes (Antebi & Dekel, 2017).

Figure 7: Number of air strikes per month during Trump's term, 2017-2019

Source: Airwars (2018); U.S. Department of Defense (n.d.)

Figure 8: Total strikes in Iraq and Syria until the end of December 2018

Source: Airwars (2018); U.S. Department of Defense (n.d.)

After a temporary slowdown between October 2018 and February 2019, the number of coalition strikes increased significantly during the battle over the last major stronghold of the Islamic State in Syria—Deir ez-Zor. Once the Kurdish forces declared final victory in the campaign against the Islamic State, the number of strikes in Syria dropped. After the start of the US withdrawal from Syria, CENTCOM and the international coalition stopped publicly reporting the number of strikes carried out in Syria and Iraq. In April 2019, the last month in which the number of strikes was published by CENTCOM, it was reported that there were no air strikes in Syria and only 28 strikes were conducted in Iraq.

Unlike other aspects of Obama's military strategy, it seems that the international coalition was an initiative that was also affirmed in theory and practice by Trump.

In January 2020, in light of the significant decline in the power of the Islamic State, the international coalition declared that it was suspending its activity in Syria and Iraq, after it had conducted over 30,000 strikes in the two countries combined. Even though the threat of the Islamic State was not fully removed by the end of 2020 and the organization continued to operate in other countries, the foreign involvement in Syria and Iraq essentially ended with the end of Trump's term as President of the United States.

In summary, the international coalition that was Obama's brainchild succeeded in operating in an organized and systematic manner for six years. Unlike other aspects of Obama's military strategy, it seems that the international coalition was an initiative that was also affirmed in theory and practice by Trump, who was not wont to criticize the existence or operation of the coalition and even continued to operate within its framework until it dissolved in early 2020.

Even though the total number of air strikes carried out during the terms of Presidents Obama and Trump were almost identical, due to the situation on the ground, most of the strikes in Iraq took place during Obama's term and most of the strikes in Syria took place during Trump's term. Between October 2014 and December 2016, 63 percent of the coalition's strikes were carried out in Iraq and 37 percent were carried out in Syria. After the first year of Trump's presidency, in which the Iraqi army achieved control over most of the conquered territories and victory was achieved in Mosul, the coalition shifted its focus onto Syria. Between January 2017 and April 2019, the opposite trend was observed—68 percent of the strikes were carried out in Syria, while only 32 percent were carried out in Iraq.

Analysis and Conclusions

The military involvement in Syria and Iraq as part of the campaign against the Islamic State relied on a military strategy that was based on three main principles: the insertion of ground forces; assistance and training for local forces; and air strikes as part of the international coalition. These were defined by Obama as guiding principles during his second term in the White House, and despite several differences, these principles continued during Trump's term. Some of the differences in strategy stemmed from Trump's personal decisions, such as deploying ground forces in the field and directly arming the Kurdish forces, and some stemmed from the situation on the ground, such as the focus of the air strikes and the continuation of the training programs.

On the issue of the military presence of US soldiers on the ground in Syria and Iraq, the main differences between Trump and Obama boil down to two aspects: how their own personal views correlated with the deployment of ground forces, and whom they chose to have the ultimate authority to adapt and adjust the number of soldiers in the field. Unlike Obama, who positioned himself as the main authority regarding the number of soldiers sent into the combat arena, upon entering the White House, Trump granted that power to the Pentagon.  While Obama related frequently to the issue of boots on the ground and its impacts on military strategy in the campaign against the Islamic State, Trump did not attribute importance to it and did not operate within the framework of its inherent constraints.

The substantive differences in how the significance of the issue was viewed were reflected clearly on the ground. During his term, Obama was very aware of the number of soldiers sent, the objectives they were sent for, and the impact of these elements on the American public. Although Obama sent about 5,500 soldiers over the course of two years into Syria and Iraq, this was still a very limited number compared to the American capabilities for ending the fighting against the Islamic State more quickly, in light of their clear military superiority.

Even when the number was high, Obama emphasized the non-involvement of the forces in active fighting that is not limited in time as a central component of the ground presence. Thus, as long as he didn't define the soldiers sent to Iraq and Syria as actively involved in the fighting, he could send hundreds and thousands of advisors, trainers, special forces, and logistical teams without violating his promises to the public. Toward the end of his term, and after ground soldiers were identified operating in the center of combat zones in Syria, Obama could no longer deny that there were soldiers on the ground in combat roles that were not there for the sole purpose of defending American civilians and facilities. In contrast, the issue of boots on the ground was completely absent from Trump's concept, and thus it did not have substantive impact on his strategy. Even though Trump decided not to publicly report the number of US soldiers sent to Syria and Iraq, this decision was not made to placate public opinion but rather in order to retain the element of surprise vis-à-vis the Islamic State. The fact that he granted the military's commanders broader decision making powers on tactical issues, including the number of forces sent into the field, was a significant change from Obama's presidency, which enabled the army to send additional forces without needing to contend with public criticism. While the number of soldiers sent did not come close to 20,000 or 30,000 soldiers as Trump initially proposed during the elections period, it was an important push for the continued battles in the field and the numbers rose more quickly and with sharper increases than during Obama's term.

On the issue of aid to local forces, the differences between Obama and Trump were generally less substantive and more specifically defined, based on individual cases. Trump continued to maintain the training programs in their original format, which were advanced during Obama's term in both Syria and Iraq. However, Trump implemented a specific change on the issue of the direct and public arming of the Kurdish forces in Syria, in order to speed up the battle for a-Raqqah and to achieve another victory over the Islamic State, after it was pushed out of Iraq.

The military strategy did not succeed in fully achieving the desires and objectives of its two presidents.

Obama's combat strategy was based on the principle of leading from behind (Dombrowski & Reich, 2018) while local forces were at the front lines of the fighting. The Iraqi government's inability to maintain governance after the withdrawal in 2011 and its powerlessness to block the Islamic State throughout 2014, along with the lack of strong partners for collaboration in Syria, challenged Obama's desire to let local forces lead the military efforts on the battlefield but did not propel him to abandon the strategy.

Obama's strategy led to the creation of two training programs. Within two years, the first trained about 25,000 people from the Iraqi defense forces, 8,500 anti-terrorism workers, and 12,000 Kurdish Peshmerga soldiers (Baron, 2017). The second trained a more limited number of Syrian rebels and operated intermittently starting in January 2015. Following in Obama's footsteps, Trump retained the support frameworks for local forces, not necessarily because he adopted Obama's strategy per se, but rather out of an existing necessity on the ground and lacking a real reason to stop the processes that had already begun. When Trump began his term as President, the training programs in Iraq and Syria stabilized and operated continuously.

Trump's most prominent change to Obama's strategy in Syria took place a few months after he entered the White House and related to the issue of arming the Kurdish rebels. During the fighting against the Islamic State, the Kurdish militia YPG (which led the SDF coalition) became one of the most important partners of the US against the Islamic State. While the United States had already granted financial support and military aid to the SDF coalition during Obama's term, recognizing the YPG as a separate entity that could be supported directly without the outer shell of the SDF coalition is what constituted the substantive change during Trump's term.

Trump's support for the Kurds proved to be an ad hoc strategic move and not an attempt to create real relations or to establish long-term support. Indeed, the direct arming of the YPG was stopped after the main goal of capturing a-Raqqah from the Islamic State was achieved. In ending support for the YPG, Trump reverted to the strategy set by Obama, but the relationship with the Kurdish rebels was significantly harmed in a way that does not seem to allow further close cooperation, if the Islamic State were to return to operate in Syria.

The establishment of the international coalition and the air strikes were another main aspect of Obama and Trump's military policy in the fight against the Islamic State. The idea of an international coalition was created out of Obama's understanding that the US entering a prolonged campaign alone would make it difficult to maintain continuous combat. The ideology of the Islamic State posed a threat to both Western and Arab elements, leading to quick responses from many countries. The fighting as part of the coalition continued steadily and supported the efforts of forces on the ground both during Obama's term and during Trump's term until the end of the overall campaign in early 2020.

The main differences between Obama and Trump are the focus of the strikes and the level of commitment to operating within a multilateral framework over time. The differences in the focus of the strikes stemmed from the situation on the ground. During Obama's term the main effort was in Iraq and during Trump's term the main effort moved to Syria. In quantitative comparison, even though Trump claimed during the elections that he would bomb the Islamic State massively, in practice the number of strikes conducted in the 29 months of the coalition's operation during Obama's term, between August 2014 and December 2016, and the 28 months of the coalition's operation during Trump's term, from January 2017 to April 2019, was almost the same. What was unusual was dropping the largest non-nuclear bomb in the American arsenal on the Islamic State's stronghold in Afghanistan, which aimed to send a message about the commitment to take severe action against external threats (Gilboa, 2017).

This study does not include a quantitative comparison of the number of armaments released in each strike or the number of civilian casualties—figures that could better indicate a difference in the intensity of the attacks under the two presidencies. However, media reports and reports by organizations such as Airwars claimed that the number of civilian casualties was significantly higher during Trump's term than during Obama's term, which could indicate Trump allowed a more permissive strike policy.

In conclusion, Obama came to the campaign against the Islamic State holding clear principles regarding the method and depth of fighting that he was willing to reach. His attempts to refrain from deploying ground forces while supporting local forces to lead the fighting and offensive air assistance provided within a multilateral international framework were the pillars of his combat strategy. Obama adhered to these principles at the expense of faster progress in the campaign. Trump's entry into the White House and his desire to end the campaign against the Islamic State quickly led to several changes in the combat strategy; some were limited in scope and depth while others were more  substantive.

Even though he tended to criticize Obama's management, the combat strategy that Trump pursued was a direct continuation of the strategic framework set by Obama at the outset of the campaign in 2014. Central changes to the strategy, such as a broader delegation of powers to the army, increasing the number of soldiers on the ground, and directly arming the Kurdish forces, aimed to advance the final combat efforts quickly, but they were made at the expense of endangering American soldiers, worsening the United States' relations with its allies, and sharpening conflicts within the administration.

Judging by outcomes, the American strategy succeeded only partially. The level of the threat posed by the Islamic State after 2020 and its ability to conquer central urban areas decreased significantly. However, as of the writing of this article, the Islamic State is still active in several countries in the Middle East and Africa, including Syria and Iraq, while continuing to carry out organized attacks, recruit new operatives, and maintain a continuous presence on social networks (al-Hajj, 2022). If the declared objectives of Obama and Trump were to defeat the Islamic State and its infrastructure to prevent any future possibility of its return to operation, the military strategy did not succeed in fully achieving the desires and objectives of its two presidents.

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