Editor's note: Peter Bergen is CNN's national security analyst, a director at the New America Foundation and the author of "Manhunt: The Ten-Year Search for bin Laden -- From 9/11 to Abbottabad."
(CNN) -- President Barack Obama is the first American president known to have authorized the assassination of a US citizen.
On September 30, 2011, Anwar al-Awlaki, a U.S. citizen by virtue of his birth in New Mexico in 1971, was killed by an American drone in Yemen along with another U.S. citizen, Samir Khan, who grew up in New York City and Charlotte, North Carolina.
Al-Awlaki had played an operational role in al Qaeda's affiliate in Yemen, al Qaeda in the Arabian Peninsula -- for instance, tasking the "underwear bomber," Umar Farouk AbdulMutallab, to bring down an American airliner over the United States.
AbdulMutallab attempted to bring down Northwest Flight 253 over Detroit on Christmas Day 2009, but luckily his underwear bomb didn't detonate correctly.
Khan had played more of a supporting role for AQAP as the editor of the group's online magazine, Inspire, which has inspired a number of terrorists, including the two brothers suspected of bombing the Boston Marathon last year.
The killings of two American citizens by a U.S. drone without a judicial process caused considerable outrage on both the left and the right.
Since then there has been far more public discussion of the secretive drone program, both by U.S. government officials, including President Obama, and at public hearings about drones in Congress. But will al-Awlaki and Khan be the last Americans to die in a U.S. drone strike?
U.S. officials are now debating whether to kill with a drone another American citizen who is part of al Qaeda and believed to be plotting attacks against the United States, a senior U.S. official tells CNN.
The Associated Press first reported this development but is withholding the name of the targeted individual.
There has been speculation but no confirmation about who the individual might be. At least a couple of other American citizens or permanent residents are known to play important roles in al Qaeda today.
One name that has been mentioned in media reports is that of California-born Adam Gadahn, who for the past decade has operated as a leading al Qaeda propagandist. In 2006 Gadahn was the first American charged with treason in more than half a century.
However, there is, at least so far, no public information that Gadahn has played an operational role in al Qaeda's terrorist plots, and therefore it is unlikely that he would be placed on a "kill list," unless his role in al Qaeda has changed of late from propagandist to operational planner.
According to a senior U.S. administration official, Gadahn is not the subject of the ongoing high-level discussions about whether a new name should be added to the kill list.
In a letter to the Senate Judiciary Committee in May 2013, U.S. Attorney General Eric Holder laid out the legal rationale the government uses to determine if an American citizen can be killed in a drone strike.
In the letter, Holder said that based on Supreme Court decisions during World War II, merely being an American citizen does not make one "immune from being targeted." Holder also asserted that an American who poses an "imminent threat of violent attack against the United States" and is in a location where capture "is not feasible" could be killed.
Holder explained that al-Awlaki "plainly satisfied all these conditions" as he had recruited the underwear bomber and instructed him to blow up an U.S. airliner "when it was over American soil." Al-Awlaki was also killed in a remote part of Yemen where a U.S. ground operation to capture him was deemed unfeasible by the Obama administration.
There is a certain irony in Holder's legal reasoning. The FBI was monitoring al-Awlaki's e-mail account for years before he was killed. To monitor his e-mail, the FBI had to get a court order.
Yet the decision to target al-Awlaki for death was made without any kind of judicial proceeding. As Vicki Divoll, a former assistant general counsel for the CIA, nicely put it a year before al-Awlaki was killed in the drone strike, "Awlaki's right to privacy exceeds his right to life."
Khan was killed in the same drone strike that killed al-Awlaki, but according to a senior U.S. official, that was unintentional and was merely a byproduct of Khan traveling in the same car as al-Awlaki when the drone strike occurred.
In sum, Khan's role as the editor of Inspire magazine was not enough to put him on a kill list.
When it comes to targeting a U.S. citizen for death, American officials, by their own account, will make particular efforts to determine how dangerous an al Qaeda operative that person really is. In the eyes of many Americans, however, a decision to kill one of their own should also be subject to judicial review.
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