A U.S. drone strike in January targeting an al Qaeda compound in Pakistan near the Afghan border inadvertently killed an American and an Italian who had been held hostage for years by the group, U.S. officials said on Thursday.
President Barack Obama apologized and took "full responsibility" for all counterterrorism operations, including this one.
The deaths were a setback for the long-running U.S. drone strike program that has targeted Islamist militants in Pakistan, Afghanistan and elsewhere, and has often drawn criticism in those countries and from civil liberties groups in the United States.
Killed in the January drone strike were aid workers Warren Weinstein, an American held by al Qaeda since 2011, and Giovanni Lo Porto, an Italian who went missing in Pakistan in 2012, as well as Ahmed Farouq, an American who was an al Qaeda leader, U.S. officials said.
Adam Gadahn, an American al Qaeda member who was charged with treason in the United States, was also killed in a separate strike on another al Qaeda camp five days later, the officials said.
Obama said he had ordered a full review of the matter to ensure such mistakes are not repeated.
"I profoundly regret what happened. On behalf of the United States government, I offer our deepest apologies to the families," Obama told reporters at the White House.
Republican House of Representatives Speaker John Boehner and other lawmakers called such a review appropriate but steered clear of criticizing the drone program. Senator Lindsey Graham of South Carolina, a Republican who is often a fierce critic of the Democratic president, said Gadahn and Farouq "got what they deserved."
U.S. officials said the drone strikes occurred inside Pakistan in the conflict-torn border region near Afghanistan. One official said the CIA had observed the compounds over some time but had no idea hostages were present.
Use of unmanned drones, which enable the United States to carry out counterterrorism operations without putting U.S. personnel directly in harm's way, has prompted criticism because of the deaths of civilians and because on occasion they have involved killing Americans abroad without judicial process.
The American Civil Liberties Union said the government should better follow its own standards before launching drone strikes. "In each of the operations acknowledged today, the U.S. quite literally didn’t know who it was killing," said Jameel Jaffer, the ACLU's deputy legal director