A convert to Sunni Islam in California at age 16 , Lindh traveled to Yemen in 1998 to study Arabic and stayed there for 10 months . He later returned in 2000 , then went to Afghanistan to aid the Taliban . He received training at Al-Farouq , a training camp associated with al-Qaeda , designated a terrorist organization by the United States and other countries . While at the camp , he attended a lecture by Osama bin Laden . After the 9/11 attacks , he remained there to join opposing military forces after he learned that the U.S. was allied with the Afghan Northern Alliance . Lindh had previously received training with Harkat-ul-Mujahideen , an internationally designated terrorist organization based in Pakistan
9/11 attacks
September 11 attacks
John Walker Lindh