Hasan Akbar, 34, now faces a possible death penalty, which the 15-member jury will consider at a hearing that begins Monday.
Prosecutors say Hasan Akbar, 33, told investigators he launched the attack because he was concerned U.S. troops would kill fellow Muslims in Iraq. They said he coolly carried out the attack to achieve "maximum carnage" on his comrades in the 101st Airborne Division.
The verdict came after 2½ hours of deliberations following seven days of testimony in a court-martial — the first time since the Vietnam era that an American has been prosecuted on charges of murdering a fellow soldier during wartime.
Akbar stood at attention as the verdict was read by the colonel who headed the jury panel, chewing his lip but giving no other outward sign of emotion. Defense attorneys acknowledged that Akbar carried out the attack, but argued he was too mentally ill to have premeditated it and was fueled by emotion.