Months after U.S. operations against terrorist groups abroad took a tragic accidental toll, President Obama spoke Thursday about a drone strike against al Qaeda that killed two aid worker hostages. Speaking from the White House press room, Obama said he took "full responsibility" for a strike on an al Qaeda compound in January that killed Warren Weinstein and Giovanni Lo Porto, aid workers who had been held by the terrorist group for years. The strike also killed an American citizen who was fighting with al Qaeda. According to the White House, no one knew that the two men were being held at the compound that was attacked. The compound was situated in the border regions of Afghanistan and Pakistan that remain a hotbed of militant activity. "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," Obama said. The White House released a statement early Thursday confirming the attempted mission and the deaths. It ended, "Many within our government spent years attempting to locate and free Dr. Weinstein and Mr. Lo Porto. The pain of their deaths will remain with us as we rededicate ourselves to adhering to the most exacting standards in doing all we can to protect the American people." This is not the first U.S. mission to end in hostage deaths. American photographer Luke Somers was killed in an attempted rescue mission gone wrong in Yemen in December 2014.