An American student in Saudi Arabia who is charged with plotting to assassinate President Bush told Saudi interrogators that "I came up with the idea on my own" because he wanted to be "the brain, the planner" for a terrorist operation, American prosecutors said in a court filing made public on Monday.

The Justice Department said the student, Ahmed Omar Abu Ali, 24, "represents one of the most dangerous terrorist threats that America faces in the perilous world after September 11, 2001: an Al Qaeda operative born and raised in the United States, trained and committed to carry out deadly attacks on American soil."