Obama Takes 'Responsibility' for Slain Hostages

President Obama said today that he takes "full responsibility" for a U.S. government counterterrorism operation that killed two innocent hostages held by al Qaeda.

Dr. Warren Weinstein, an American held by the terror group since 2011, and Giovanni Lo Porto, an Italian national who had been an al Qaeda hostage since 2012, were "accidentally" killed in a U.S. operation in January, the president acknowledged.

"I want to express our grief and condolences for the families of two hostages," Obama said from the White House briefing room, noting that at the time, the U.S. believed no civilians were present at the operation site.

"Since 9/11, our counterterrorism efforts have prevented terrorism attacks and saved innocent lives, both here in America and around the world, and that determination to protect innocent life only makes the loss of these two men especially painful for all of us," he added. "It is a cruel and bitter truth that in the fog of war generally and our fight terrorists specifically, mistakes, sometimes deadly mistakes, can occur. But one of the things that sets America apart from many other nations, one of the things that makes us exceptional is our willingness to confront squarely our imperfections and to learn from our mistakes."

A U.S. government official told ABC News that the drone strike that killed Weinstein and LoPorto occurred on January 14 and targeted a compound in Pakistan's tribal area suspected of being used by al Qaeda.

The official said there was "near certainty" that there were no non-combatants at the location.

White House Press Secretary Josh Earnest told reporters today that the compound had received hundreds of hours of overhead surveillance prior to the drone strike. The U.S. official said Weinstein and LoPorto were likely "hidden and well concealed" which is why the surveillance did not indicate they were there.

According to Earnest, just weeks after the strike, initial indications emerged that Weinstein may have been killed. It was not until a few days ago that the U.S. intelligence community assessed with a high degree of confidence that Weinstein and LoPorto had been killed in the strikes.

The official said that the strikes did not receive Presidential approval as they were conducted within the bounds of existing legal guidelines for such strikes.

Though the administration asserted in a statement that the drone operation was "lawful and conducted consistent with our counter-terrorism policies," President Obama promised a thorough independent review, saying he declassified the mission "because the Weinstein and Lo Porto families deserve to know the truth."

In a video released by al Qaeda in 2012, Weinstein, a former peace corps and U.S. aid official abducted from his home in Lahore, Pakistan, pleaded with Obama to comply with the terrorists' demands.

"My life is in your hands, Mr. President," he said. "If you accept the demands, I live. If you don't accept the demands, then I die."

"I've done a lot of service for my country, and I would hope that my country will now look after me and take care of me and meet the demands of the mujahedeen," he added.

Since Weinstein's abduction, government officials had worked "tirelessly" to bring him home safely, Obama said today.

"For decades, Warren lived the ideals of our country," he said. "He was a loving husband, father, and grandfather, who willingly left the comforts of home to help the people of Pakistan."

"We are devastated by this news and the knowledge that my husband will never safely return home," Weinstein's wife, Elaine, said in a statement.

"Unfortunately, the assistance we received from other elements of the U.S. Government was inconsistent and disappointing over the course of three and a half years. We hope that my husband's death and the others who have faced similar tragedies in recent months will finally prompt the U.S. Government to take its responsibilities seriously and establish a coordinated and consistent approach to supporting hostages and their families," she said.

While the family looks forward to the results of the U.S. government's investigation into the operation, "those who took Warren captive over three years ago bear ultimate responsibility," she added. "The cowardly actions of those who took Warren captive and ultimately to the place and time of his death are not in keeping with Islam and they will have to face their God to answer for their actions."

According to a White House statement, "two other Americans were recently killed in U.S. Government counter-terrorism operations in the same region."

Ahmed Farouq and Adam Gadahn were both American members of al Qaeda, but neither was "specifically targeted," the White House says.

Farouq was killed in the January 14 strike that killed Weinstein and LoPorto. Gadahn, a well-known al-Qaeda spokesman was killed in a drone strike on January 19.

ABC News' Mary Bruce, Karen Travers and Cindy Smith contributed to this report.

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