This September 25, 2009 OLC memo from John Yoo finds that in response to the 9/11 terrorist attacks, the President has the constitutional power to 1) retaliate against any person, organization, or state suspected of involvement in these attacks as well as foreign states suspected of harboring or supporting such organizations and 2) deploy military force against terrorist organizations or foreign states suspected of harboring or supporting them, whether or not they can be specifically linked to the 9/11 terrorist attacks.