Perhaps somebody would like to read the Joint Resolution of the US House and Senate that was signed into law on 18 SEP 2001.

{excerpt}

This joint resolution may be cited as the `Authorization for Use of Military Force'.

SEC. 2. AUTHORIZATION FOR USE OF UNITED STATES ARMED FORCES.

(a) IN GENERAL- That 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, or harbored such organizations or persons, in order to prevent any future acts of international terrorism against the United States by such nations, organizations or persons.


{note: vote in Senate was 98-0...unanimous and bi-partisan}