Marines are regularly flying over both Iraq and Syria to provide an airborne force capable of responding quickly if a coalition aircraft goes down and a pilot or air crew needs rescuing, said the commanding officer of a unit that returned from Iraq this fall.

Col. Jay Bargeron, commander of the Marine task force, said the tactical recovery of aircraft and personnel (TRAP) mission put his Marines in the air on an almost weekly basis, based on threat assessments and what operations were underway. A platoon of Marines typically split into two MV-22 Ospreys, aircraft that are capable of taking off like a helicopter but flying like an airplane. A KC-130 tanker plane also was deployed each time to provide refueling for the Ospreys and allow them to stay in the air.

“Sometimes we would be on a shorter alert than others, and sometimes we would cover periods of strike packages for longer periods of times than others,” said Bargeron in a meeting with reporters at the Pentagon on Tuesday. “But we had to be ready to be assigned each day.”

Bargeron led what the service calls a special-purpose Marine air ground task force, or SPMAGTF. It had more than 2,300 Marines and was devoted to crisis-response missions across the Middle East, but the majority of its forces were concentrated in Iraq as part of Operation Inherent Resolve, the mission against the Islamic State militant group. A similar unit replaced Bargeron’s and will rotate out next year.

The “airborne TRAP” assignments raise the prospect that the U.S.-led military coalition will be able to respond quickly if an aircraft goes down, but also puts the Marines in harm’s way in volatile airspace and over a war zone.

As described by Bargeron, it also includes an expansion when compared to previous rotations of Marines in Iraq. The officer who led the previous Marine task force, Col. Jason Bohm, told reporters in May that Marines deployed an airborne TRAP unit in December after a Jordanian F-16 crashed in Syria, but would not say whether or not say that Marines crossed into Syrian airspace, as Bergeron did on Tuesday.

The pilot of the Jordanian jet, Lt. Muath al-Kaseasbeh, was eventually killed by the Islamic State. The Marine mission to recover him was called off after it was determined he already had been captured by the militants, Bohm said.

The Marine task force had troops distributed across several bases, including Al Asad and Al Taqaddum air bases and the U.S. Embassy in Baghdad. On one occasion, Marines from the unit were sent to recover undisclosed sensitive items from an MQ-1 Predator drone that crashed in southern Iraq in July, Bargeron said.

He said the Marines received their assignments from the Qatar-based Combined Air Operations Center, which serves as a nerve center that oversees air operations across the Middle East for the U.S. military.