This Dana Priest article is interesting for the way it fleshes out the way the US is working in Yemen (primarily), Pakistan, and Somalia. But note this line, which she kind of buries in there.

As part of the operations, Obama approved a Dec. 24 strike against a compound where a U.S. citizen, Anwar al-Aulaqi, was thought to be meeting with other regional al-Qaeda leaders. Although he was not the focus of the strike and was not killed, he has since been added to a shortlist of U.S. citizens specifically targeted for killing or capture by the JSOC, military officials said. [my emphasis]

That is, somewhere there’s a list of Americans who, the President has determined, can be killed with no due process.

Priest goes on much later in the article.

After the Sept. 11 attacks, Bush gave the CIA, and later the military, authority to kill U.S. citizens abroad if strong evidence existed that an American was involved in organizing or carrying out terrorist actions against the United States or U.S. interests, military and intelligence officials said. The evidence has to meet a certain, defined threshold. The person, for instance, has to pose “a continuing and imminent threat to U.S. persons and interests,” said one former intelligence official.

The Obama administration has adopted the same stance. If a U.S. citizen joins al-Qaeda, “it doesn’t really change anything from the standpoint of whether we can target them,” a senior administration official said. “They are then part of the enemy.”

Both the CIA and the JSOC maintain lists of individuals, called “High Value Targets” and “High Value Individuals,” whom they seek to kill or capture. The JSOC list includes three Americans, including Aulaqi, whose name was added late last year. As of several months ago, the CIA list included three U.S. citizens, and an intelligence official said that Aulaqi’s name has now been added. [Update, February 17, 2010: WaPo has since retracted the report that CIA had US citizens on its kill list.]

Of course, they said Jose Padilla had close ties to al Qaeda, but those turned out to be more tenuous than originally claimed. Likewise the case against John Walker Lindh. And there are any number of “aspirational” terrorists whom officials have claimed had joined al Qaeda.

But I guess the tenuousness of those ties don’t really matter, when the President can dial up the assassination of an American citizen.