US Military Involvement in the Anti-ISIS Effort Won't Avoid Frontline Engagement: The Role of American Ground Forces in the ISIS Battle Campaign

US Military Involvement in the Anti-ISIS Effort Won't Avoid Frontline Engagement: The Role of American Ground Forces in the ISIS Battle Campaign

U.S. Ground Forces in Operation Inherent Resolve: Enablers and Advisers in the Fight Against ISIS

Operation Inherent Resolve, launched in 2014, was a U.S.-led coalition mission aimed at defeating the Islamic State (ISIS) in Iraq and Syria. The operation, which involved extensive airstrikes and ground support to local partner forces, marked a significant international effort to dismantle ISIS's caliphate and eliminate its fighters.

Leadership and Scope

The operational mission to set the conditions for Mosul involved seizing key terrain, establishing bridge crossings, and generating firing positions and assembly areas for an eventual assault on Mosul. The project leaders on this study were senior researchers Jeff Martini, Sean Zeigler, and Gian Gentile at the RAND Corporation.

Ground Forces Role

Initially, the U.S. refrained from deploying large ground combat forces directly, instead employing an advisory and support role with local allied forces such as the Iraqi military and Kurdish-led Syrian Democratic Forces (SDF). As the fight progressed, U.S. forces became more directly involved, with approximately 3,000 troops in Syria by early 2019, providing air cover, logistics, intelligence, and ground coordination. US forces were also engaged in raids and direct action missions, such as the killing of senior ISIS leaders.

Progress and Endgame

The coalition's air and ground operations gradually reduced ISIS territorial control, culminating in the 2018–2019 final battles in eastern Syria, where U.S. support helped the SDF defeat ISIS remnants in key pockets such as Al-Baghuz Fawqani. Despite declared territorial defeat by 2018, U.S. forces continued counterterrorism operations, including targeted raids killing ISIS leaders in 2025.

Casualties and Challenges

The campaign involved significant destruction and civilian harm allegations due to coalition strikes, with thousands of civilian casualties documented or alleged, emphasizing the complexity of urban counterinsurgency warfare.

Command and Regional Stability Efforts

U.S. Central Command (CENTCOM) routinely supervises OIR operations. The coalition emphasizes partnership building with regional militaries to maintain pressure on ISIS and ensure long-term stability. Command transitions occurred regularly to adapt strategy and sustain momentum.

Notes

• The views expressed in this article do not reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense.
• Some US advisors were authorized to move as close as the last covered and concealed position before the front line during the Mosul operation.
• US Apache squadrons conducting close combat attack were crucial in attriting ISIS forces on the west bank of the Tigris, enabling Iraqi security forces to maneuver through what was considered the teeth of ISIS defenses.
• Iraqi surrogate forces bore the brunt of frontline fighting, while US forces were also engaged in on-the-ground combat operations.
• Field-grade officers were empowered to approve certain strikes, an authority previously held at the one-star level.
• Ashton Carter, the Secretary of Defense, announced new policy decisions, including the use of US Army artillery regiments and Apache squadrons to attrit ISIS prior to the advance of Iraqi security forces.
• The changes in authority provided tactical advantages and strengthened Iraqis' resolve by demonstrating higher levels of US commitment to the fight.
• Doubts existed about the coalition's ability to expel ISIS from Iraq.
• The Global Coalition to Defeat ISIS was formed in 2016.
• The operational mission to liberate Fallujah and Ramadi posed fewer operational hurdles compared to the coming fight along the Tigris and the battle to liberate Mosul.
• The report focuses on the role of US ground forces in the fight to defeat ISIS in Iraq.
• The fight to defeat ISIS required a ground war, with grueling liberation of territory kilometer by kilometer.
• The lessons from Inherent Resolve suggest that "by, with, and through" does not eliminate the need for direct combat by US forces.
• The operation culminated in the seizure of Qayyarah West airfield, which is within artillery range of Mosul.
• The battles to liberate Fallujah and Ramadi took place in 2016.
• The operational history of Operation Inherent Resolve is not easily replicable in other contexts due to the prior US experience in the country and the unique circumstances of the operation, such as the weak military capabilities and rudimentary command-and-control attributes of ISIS.

1. The U.S. military, through Operation Inherent Resolve, played a strategic role in counterterrorism against ISIS, providing air cover, logistics, intelligence, and ground coordination, as well as engaging in raids and direct action missions.
2. As the fight against ISIS progressed, U.S. forces became more directly involved, with approximately 3,000 troops in Syria by early 2019, forming an advisory and support role with local allied forces like the Iraqi military and the Kurdish-led Syrian Democratic Forces (SDF).
3. The operation, which involved extensive airstrikes and ground support to local partner forces, underscores the ongoing commitment of the U.S. in war-and-conflicts, demonstrating a political will to maintain long-term stability in the region.
4. Despite the declared territorial defeat of ISIS by 2018, U.S. forces continued counterterrorism operations, including targeted raids killing ISIS leaders in 2025, signifying the enduring challenge of warfare and the need for ongoing military defense strategies.

Read also: