A member of the FBI’s Hostage Rescue Team in training. (FBI photo)

The capture of one of the alleged leaders of the 2012 terrorist attacks in Benghazi, Libya, in a joint raid involving U.S. Special Operations troops and the FBI highlights the bureau’s role as an international anti-terrorism force.

The Defense Department declined on Tuesday to name the units that captured Ahmed Abu Khattala, whom the State Department identified in January as a terrorist and a “senior leader” of the Ansar al-Shariah militia group. But it follows a mission in October in which the U.S. Army’s elite Delta Force and members of the FBI’s Hostage Rescue Team abducted Nazih Abdul-Hamed al-Ruqai, an accused member of al-Qaeda, in a mission in the Libyan capital.

The FBI HRT, a domestic counter-terrorism unit prior to the 9/11 attacks, has become a de facto Special Operations force in its own right. While U.S. Special Operations units have frequently used the FBI for its domestic crime analysis of organizations like al-Qaeda, the use of the hostage rescue team as a “direct-action” force outside the United States is a relatively new development.

The close relationship between the HRT and the U.S. military’s most elite units has existed since the HRT’s inception in the early 1980s, The Washington Post reported earlier this year. The HRT’s first commander, Danny Coulson, said at the time that nearly all of the initial members of the HRT had trained with Delta Force. The team itself is located on the Marine Corps base in Quantico, Va.

In addition to intensive FBI-led training, many members of the HRT are trained by some of the U.S. military’s elite units; many HRT members work as liaisons with other Special Operations units. HRT members frequently attend schools hosted by military units, including U.S. Navy SEALS, according to a 2013 article in The Week.

In an interview, Shane Gibney, a former active-duty Marine sergeant who worked extensively with the FBI’s HRT as a scout-sniper instructor at Quantico, said it’s natural to have HRT members working with Special Operations troops.

“Half of the HRT guys are former military and special ops, so that really helps with the training,” he said.