"My complicity was on behalf of a government that openly acknowledges that it would hate for the law of Almighty Allah to be the supreme law of the land," Maj Nidal Malik Hasan said in a statement released to Fox News.
He then asks rhetorically whether that amounts to a war on Islam, and then replies, "You bet it is and I participated in it."
Hasan, of Palestinian origin, also criticised US policy in the Middle East towards the Palestinians.
Hasan, 42, is charged with killing 13 people and injuring over 30 others in the November 5, 2009 attack at the Fort Hood army base and faces the death penalty if convicted.
The judge in Hasan's case recently ruled that he cannot argue as part of his defence that the shooting was an effort to protect Taliban leaders in Afghanistan - the so-called "defence of others" strategy.
Hasan is serving as his own attorney and in that role has spoken more often during pre-trial hearings or jury selection.