(Nearly) unanimous Congressional Resolution: "the President is authorized to use all necessary and appropriate force against those nations, organizations, or persons he determines planned, authorized, committed, or aided the terrorist attacks that occurred on September 11, 2001"
Notice the Resolution says "persons," not "non-citizens." This Resolution mirrors the congressional authorization to use force given Adams in 1798. A good many of the Founders being involved in its production.
http://en.wikipedia.org/wiki/Act_Further_to_Protect_the_Commerce_of_the_United_States
BTW, anytime Congress decides to it can rescind its authorization.
Did this guys son aid, abet, or plan the attack that occurred on 9-11?