As a general principle, international law permits the use of lethal force against individuals and groups that pose an imminent threat to a country, and officials said that was the standard used in adding names to the list of targets.

People on the target list are considered to be military enemies of the United States and therefore not subject to the ban on political
assassination first approved by President Gerald R. Ford.

Both the C.I.A. and the military maintain lists of terrorists linked to Al Qaeda and its affiliates who are approved for capture or killing, former officials said. But because Mr. Awlaki is an American, his inclusion on those lists had to be approved by the National Security Council, the officials said.

Source: http://www.legitgov.org/#breaking_news, 06 Apr 2010