San Juan, Puerto Rico ? A Muslim chaplain at the U.S. military base in Guantanamo who counseled suspected terrorists and taught fellow troops about Islam is the first known U.S. soldier to be detained in the U.S.-led war on terror.

Army Capt. Yousef Yee, a 34-year-old who converted to Islam after being raised as a Christian, arrived at Guantanamo Bay Naval Station in Cuba last November. His job was to teach fellow troops about Islam and counsel detainees suspected of links to Afghanistan’s ousted Taliban regime or the al-Qaida terror network.

Military officials said Saturday that Yee — who was born James Yee but later took the Muslim name of Yousef — was detained on Sept. 10 in Jacksonville after returning from Guantanamo. He has not been charged.

A senior law enforcement official, speaking on condition of anonymity, said FBI agents confiscated classified documents Yee was carrying and questioned him before he was handed over to the military.

Bill Hurlburt, a spokesman with the FBI in Jacksonville, Fla., confirmed that agents were at the scene, but he declined further comment.

Yee is being held at a military brig in Charleston, S.C.

“He had daily access to the detainees,” said Capt. Tom Crosson, a spokesman for U.S. Southern Command in Miami. “He is the first U.S. soldier that I know of to be detained and held since the war on terror began.”

This year, Army Sgt. Hasan K. Akbar, a 32-year-old Muslim, was charged in a March grenade attack in Kuwait that killed Air Force Maj. Gregory Stone, 40, and Army Capt. Christopher Scott Seifert, 27, and injured 14 others.

Akbar, however, was not accused of terrorism. He was charged with premeditated murder and attempted murder.