A U.S. man described as the first from the country to join the Al-Qaeda militant group after it conducted the 9/11 attacks has said the experience did not live up to his expectations.

Bryant Neal Viñas, a Catholic-born Hispanic-American originally from Queens and raised in suburban Long Island, was detained in 2008 by Pakistani security forces on terror charges and was later transferred to U.S. military custody, with whom he cooperated extensively. Writing about his experience for the first time, Viñas collaborated with security analyst Mitchell Silber in the latest issue of the Combating Terrorism Center at the U.S. Military Academy’s Sentinel magazine published Monday.

Viñas had a failed stint in the Army and enjoyed risky travel to places such as Cuba—at a time when nearly all travel to the communist-run island for U.S. citizens was restricted—before converting to Islam and traveling to Pakistan on the eve of the sixth anniversary of 9/11 in 2007 to join Sunni Muslim militants.