Operation Inherent Resolve

Overview

Operation Inherent Resolve is the U.S.-led coalition campaign against the Islamic State in Iraq and Syria. The United States and its international partners launched the campaign in 2014 in response to the Islamic State’s offensive in Iraq. The coalition first deployed to Iraq and later expanded operations into Syria, combining air power, intelligence, training, equipment and logistics with the efforts of local forces. Its central coordinating body, Combined Joint Task Force–Operation Inherent Resolve, directed coalition military activity across both countries. Kuwait hosted the task force’s headquarters.

In Iraq, the coalition worked with Iraqi security forces to recover cities and degrade the Islamic State’s military and defensive capabilities. In Syria, coalition aircraft struck the group’s fighters, commanders and infrastructure while U.S. special operations forces conducted raids and advised local partners. The Syrian Democratic Forces became the principal coalition partner on the ground in Syria; U.S. Special Forces also advised and assisted the People’s Defense Units. Peshmerga forces fought the Islamic State as part of the wider campaign. The partnership allowed coalition forces to apply air support and other capabilities in coordination with forces engaged directly on the ground.

The Islamic State’s loss of its final territorial enclave in March 2019 marked a decisive military achievement. It did not end the threat posed by surviving cells, attack planners and the group’s detention network in Syria. U.S. forces shifted toward training and advising local partners while continuing operations against Islamic State remnants. The campaign remained active into 2026, alongside plans to change the coalition’s military presence in Iraq and sustain support for operations in Syria.

Background

The Islamic State’s 2014 offensive in Iraq gave the United States and its partners an immediate military objective: halt the group’s advance and help Iraqi forces recover territory. The coalition’s mission developed into a campaign across Iraq and Syria because the Islamic State held territory, operated military infrastructure and moved personnel across both countries. Its control of cities and oil facilities supported recruitment, coercion and financing. Coalition operations therefore targeted both its battlefield forces and the assets that helped it maintain territorial rule.

Combined Joint Task Force–Operation Inherent Resolve brought international military contributions under a shared campaign structure. In Iraq, cooperation with Iraqi security forces supplied local ground forces with coalition air support, training, intelligence and other assistance. In Syria, coalition forces worked with local partners while striking Islamic State positions and infrastructure. These arrangements reflected the campaign’s central method: enable forces in each country to retake and secure territory while coalition personnel supplied capabilities those forces needed.

By the campaign’s two-year assessment, the Islamic State’s military and defensive capabilities in Iraq had been substantially degraded. It had conducted no major offensive military operation since its capture of Ramadi and Palmyra in May 2015. Coalition operations had also retaken about 20 percent of the territory the group had held in Syria. Losses of territory diminished its ability to recruit, instill fear and exploit oil holdings, even as it retained significant positions in both countries.

Course of the war

The campaign’s early phase concentrated on the Islamic State offensive in Iraq. Coalition forces partnered with Iraqi security forces to liberate key cities, using air support and other assistance to help ground units advance. By 2016, the partnership had weakened the group’s capacity to defend its holdings. Ramadi and Fallujah were among the Iraqi cities recovered from Islamic State control. The effort culminated in a major offensive against Mosul, the group’s last major stronghold in Iraq.

On October 17, 2016, Iraqi Prime Minister Haider al-Abadi announced the operation to retake Mosul. Iraqi security forces advanced with coalition air support, entering eastern Mosul by the end of that year. The battle formed part of a wider series of operations that stripped the Islamic State of territory in 2016 and 2017. Increased U.S.-led air support helped local forces in Iraq and Syria press the group’s defenses and recover cities and transit routes.

In Syria, coalition aircraft supported allied ground forces and struck Islamic State commanders, military positions and economic assets. Airstrikes destroyed ground assets that included oil infrastructure, reducing resources available to the group. U.S. Special Forces advised and assisted the People’s Defense Units and carried out raids during the campaign. The Syrian Democratic Forces, which included the People’s Defense Units, became a central coalition partner. Its operations included the recovery of Manbij, while pressure increased around Raqqa, which the Islamic State had used as an administrative center and base for external plotting.

The scale and range of the coalition’s air campaign were evident on July 27, 2017. Coalition forces carried out four strikes against Islamic State targets in Iraq and 17 in eastern Syria, including around Deir ez-Zor and Raqqa. The Syrian strikes destroyed oil refining facilities, a communications center and air defense systems, among other targets. Such attacks supported advances by local forces while damaging the infrastructure the Islamic State used to fight, communicate and draw income from its holdings.

Coalition support to local groups was tied to the anti-Islamic State mission. In July 2017, the coalition stopped supporting the Al-Qaryatayn Martyrs Brigade after it conducted operations outside the Al-Tanf de-escalation zone without coalition coordination. The United States demanded the return of weapons supplied to the brigade for fighting the Islamic State. The decision illustrated the limits placed on coalition assistance when a partner’s operations departed from the agreed mission.

Operations in eastern Syria intensified later in 2017. A coalition airstrike near Al-Mayadin on September 4 killed two senior Islamic State external operatives. That month, coalition forces supplied equipment, training, intelligence and logistics for the Syrian Democratic Forces’ Island Storm offensive toward the Euphrates near Deir ez-Zor. The offensive extended pressure on the Islamic State’s eastern Syrian positions as its territorial holdings contracted.

Fighting continued around the group’s remaining Syrian positions in 2018. In December, Islamic State fighters used a hospital in Hajin to fire on Syrian Democratic Forces personnel. The incident placed military activity within a civilian facility during the struggle for the group’s remaining territory. Coalition aircraft and Syrian Democratic Forces continued their campaign until the Islamic State lost its final territorial enclave in March 2019. The territorial defeat ended its ability to govern a continuous enclave in Iraq and Syria, but did not eliminate its members or its capacity to organize attacks.

U.S. Special Operations forces killed Islamic State leader Abu Bakr al-Baghdadi during an October 26, 2019, raid in northern Syria. The raid removed the leader who had presided over the group’s territorial expansion. It was followed by continued operations against Islamic State personnel rather than an end to the campaign. In January 2020, Syrian Democratic Forces and coalition troops apprehended 16 Islamic State operatives in Deir ez-Zor Province.

Coalition activity faced a separate threat at Iraqi facilities. Repeated rocket attacks by Kata’ib Hezbollah on bases hosting coalition troops led U.S. forces to pause operations against the Islamic State on January 5, 2020. Protection of those bases took priority over support to Iraqi partners’ operations. The pause showed how attacks on coalition facilities could interrupt the campaign even after the Islamic State’s territorial defeat.

Terrorist tactics and propaganda

The Islamic State used territorial control to sustain more than a conventional battlefield force. Its holdings gave it access to oil infrastructure, routes between Iraq and Syria, and places from which to recruit and coerce people under its rule. Coalition strikes on refining facilities and other assets sought to weaken those advantages. As the group lost cities and territory, its ability to draw recruits, impose fear and profit from oil declined. Its battlefield losses also constrained the environment in which it could organize external attacks.

The coalition targeted personnel involved in the group’s communications, recruitment, financing and attack planning. Strikes against senior operatives were intended to disrupt the networks that carried its messages and supported attacks beyond the immediate front. The September 2017 strike near Al-Mayadin killed two senior external operatives, while later raids continued to pursue members who planned attacks in Iraq and Syria. The Islamic State’s use of the Hajin hospital as a firing position in December 2018 showed another feature of its battlefield conduct: the placement of armed activity inside a civilian facility.

After the fall of its last enclave, the Islamic State remained a security threat through surviving cells and personnel held in Syria. The Syrian Democratic Forces’ detention of tens of thousands of Islamic State-affiliated men, women and children from more than 60 countries became a major continuing burden. Detention, security and the prospect of renewed activity were therefore connected parts of the post-territorial mission. Coalition and local forces continued searches, arrests and raids to prevent remnants from rebuilding operational networks.

Outcome

The coalition and its Iraqi and Syrian partners dismantled much of the Islamic State’s territorial control. Iraqi security forces recovered key cities with coalition support, while Syrian Democratic Forces and other local partners pressed the group in Syria. The loss of its final territorial enclave in March 2019 was the campaign’s clearest military result. Territorial defeat reduced the Islamic State’s ability to command a standing force, hold population centers and exploit economic assets, particularly oil infrastructure.

Military success changed the campaign’s purpose rather than bringing all operations to a close. After March 2019, U.S. forces in Syria adopted a lighter mission centered on training and advising local partners against surviving Islamic State forces. Airstrikes, raids and joint operations still addressed members capable of planning or carrying out attacks. The detention of Islamic State affiliates in Syria created a continuing security responsibility for the Syrian Democratic Forces and their coalition partners.

The campaign also left Iraq and Syria with different operational roles. Iraq had been the initial focus of the 2014 response and remained essential to the support of U.S. operations in Syria. Personnel and infrastructure based in Iraq substantially supported those continuing operations. Syria remained the site of coalition work with local partners against Islamic State remnants, including areas where the group’s former networks had operated.

Aftermath and legacy

Coalition assistance continued in Syria during 2025. In April, U.S. troops at Tanf trained Syrian Free Army soldiers in personnel and vehicle searches and checkpoint operations. The training formed part of the continuing effort to strengthen local forces against Islamic State activity. The American-led coalition also maintained several bases in the Qamishli area, while the United States retained around 1,400 troops in Syria to address the continuing threat.

The command structure remained active. Combined Joint Task Force–Operation Inherent Resolve transferred command to U.S. Army Brigadier General Kevin J. Lambert on July 22, 2025. On August 19, U.S. forces carried out a raid in Atmeh in northwest Syria that killed a senior Islamic State member. The target was a financier who planned attacks in Syria and Iraq. The operation demonstrated the campaign’s continued focus on individuals capable of sustaining the group’s networks after its territorial defeat.

Plans for Iraq called for coalition military sites there to close by September 2025, while retaining a partial U.S. presence through at least 2026 to support operations against the Islamic State in Syria. This transition reflected the shift from a large territorial campaign to narrower cooperation against surviving forces. It also underscored the logistical connection between the two countries: facilities and personnel in Iraq remained important to operations across the border.

During January–March 2026, the United States worked toward bilateral cooperation with Syria to suppress remaining Islamic State forces. The effort accompanied the existing coalition mission and its support for local partners. Operation Inherent Resolve’s legacy is therefore twofold: the coalition helped end the Islamic State’s territorial rule, while its later operations addressed the surviving cells, attack planners and detention burden left by that defeat.