“On September 25, 2001, I [Deputy Chief in the Office of Legal Counsel (OLC), John Yoo] signed an OLC opinion issued to the White House which concluded that a foreign attack had occurred on September 11, the United States was at war, and President Bush had full constitutional authority to launch attacks to destroy the enemy. President Bush had the power ‘not only to retaliate against any person, organization, or state suspected of involvement in terrorist attacks on the United States, but also against foreign states suspected of harboring or supporting such organizations.’ This power was not punitive. It included the power ‘to deploy military force preemptively against terrorist organizations.’ ”
– John Yoo, War By Other Means, Page 10