The high-profile US drone strike that killed American-born radical preacher Anwar al-Awlaki in Yemen was partly conducted from a secret air base in Saudi Arabia, the Washington Post reported Wednesday.
The base was established two years ago as part of US efforts to intensify the pursuit of Al-Qaeda in the Arabian Peninsula, a grouping of the Yemeni and Saudi offshoots of the global terror network, the newspaper said.
The disclosure of Saudi Arabia's role in the drone program that is run by the CIA and US military's Joint Special Operations Command is likely to add to debate and increasing scrutiny about whether use of such strikes is legal.
The September 2011 killing of Awlaki stoked concern because he and Samir Khan, a Pakistani-American who also died in the strike, were US citizens who had never been charged with a crime.
The White House on Tuesday defended drone strikes against Al-Qaeda suspects as legal, ethical and wise and insisted that they complied with US law and the constitution, even if they targeted Americans.
The continued focus on drones comes as White House counter-terrorism chief John Brennan goes before the Senate on Thursday for hearings on his nomination to be head of the CIA.
Brennan has been a central player in the US drone campaign, which has expanded sharply under President Barack Obama despite qualms about its legality and public outrage in Pakistan over civilian deaths.
Brennan, who once served as the CIA's station chief in Saudi Arabia, played a key role in negotiations that led to the drone base being established in the kingdom, according to the Post report.
The newspaper said it decided to reveal the location of the drone base after learning on Tuesday that another US media outlet was about to do so, ending an informal arrangement with news organizations not to publish such details.
A Justice Department memo published by NBC News on Tuesday argued that Americans high up in Al-Qaeda could be lawfully killed, even without evidence they are actively plotting an attack.
"We conduct those strikes because they are necessary to mitigate ongoing actual threats, to stop plots, to prevent future attacks and, again, save American lives," White House spokesman Jay Carney said of the memo.