These killings have been abroad, but these things proceed incrementally.
http://abcnews.go.com/Politics/eric-holder-americans-killed-drones/story?id=19236300
Attorney General Eric Holder has disclosed in a letter to Congress that four Americans were killed by U.S. drones in the course of the government's attacks on terrorists.
"Since 2009, the United States, in the conduct of U.S. counterterrorism operations against al-Qaida and its associated forces outside of areas of active hostilities, has specifically targeted and killed one U.S. citizen, Anwar al-Aulaqi," Holder wrote.
"The United States is further aware of three other U.S. citizens who have been killed in such U.S. counterterrorism operations over that same time period: Samir Khan, 'Abd al-Rahman Anwar al-Aulaki and Jude Mohammed. These individuals were not (it is claimed) specifically targeted by the United States," Holder wrote.
Previous to 2009,
http://www.juancole.com/2013/05/continue-targeted-killing.html
At least three additional US citizens have been killed in US drone attacks. In the first ever drone strike outside a battlefield, US citizen Kamal Darwish was among six men killed by the CIA in Yemen in 2002. The Bush administration insisted at the time that the intended targets were alleged al Qaeda suspects accompanying Darwish in the vehicle.
And veteran Washington reporter Bob Woodward has revealed that on November 7 2008, many Westerners, including some US passport holders died in an attack near Miranshah in North Waziristan.
As Woodward noted in his book Obamas Wars, in a subsequent meeting with Pakistans President Zardari The CIA would not reveal the particulars due to the implications under American law. A top secret CIA map detailing the attacks had been given to the Pakistanis. Missing from it was the alarming fact about the American deaths
The CIA was not going to elaborate.