Leak ended informant's rare opportunity, U.S. officials say WASHINGTON - Disclosure of a highly classified intelligence operation in Yemen last year compromised an exceedingly rare and valuable espionage achievement: an informant who had earned the trust of hardened terrorists, according to U.S. officials. The operation received new scrutiny this week after the Justice Department disclosed it had obtained telephone records for calls to and from more than 20 lines belonging to the Associated Press news service and its journalists in April and May 2012 in a high-level investigation of the alleged leak of classified information. The informant, a British citizen born in Saudi Arabia, had been recruited by British intelligence to operate as a double agent within the group Al Qaeda in the Arabian Peninsula, one of the most dangerous franchises of the Al Qaeda terrorist network. His access led to the U.S. drone strike that killed a senior Al Qaeda leader, Fahd Mohammed Ahmed Quso, on May 6, 2012. U.S. officials say Quso helped direct the terrorist attack that killed 17 sailors aboard the U.S. guided-missile destroyer Cole in a Yemeni harbor in October 2000. The informant also convinced members of the Yemeni group that he wanted to blow up a U.S. passenger jet on the first anniversary of the U.S. attack that killed Osama bin Laden in Pakistan. They outfitted him with the latest version of an underwear bomb designed to pass metal detectors and other airport safeguards, officials say. The informant left Yemen and delivered the device to his handlers, and it ultimately went to the FBI's laboratory in Quantico, Va. Intelligence officials hoped to send him back to Yemen to help track more bomb makers and planners, but the leak made that impossible, and sent Al Qaeda scrambling to cover its tracks, officials said. The Associated Press distributed a wire story on May 7, 2012, that disclosed some details of the passenger jet plot. The news agency had held the story for five days at the CIA's request. The Associated Press did not mention the informant in its report. But White House counter-terrorism advisor John Brennan, who is now CIA director, briefed several former senior government officials who would be appearing on TV. Brennan told them, he later told Congress, that U.S. authorities had "inside control" of the plot. Other media, including the Los Angeles Times, subsequently reported the use of a double agent. British intelligence officials were furious at the disclosures, a British diplomat said. And U.S. intelligence and law enforcement officials were aghast. "I have to say that this is among, if not the most serious, in the top two or three most serious leaks that I've ever seen," Atty. Gen. Eric H. Holder Jr. told reporters this week. It put the American people at risk - and that is not hyperbole. The Al Qaeda branch in Yemen certainly has tried. In December 2009, the group outfitted a passenger with an underwear bomb to bring down a jetliner over Detroit, but the bomb malfunctioned. The group also tried to blow up two U.S. cargo planes headed to Chicago in October 2010, but authorities found the bombs after getting a tip from Saudi intelligence. Intelligence officials are especially frustrated because they have struggled to penetrate Al Qaeda's senior ranks. In 2009, the CIA thought it had recruited a Jordanian doctor who had access to top Al Qaeda leaders in Pakistan. But he was still secretly loyal to the terrorist network, and he detonated a suicide bomb at a CIA base in Khowst, Afghanistan, that killed nine people, including seven with the CIA. Over the last year, the CIA and U.S. special operations forces have made significant gains against the Yemeni branch of Al Qaeda. Drone strikes have killed senior operatives, and U.S. intelligence has helped the pro-American government there drive Islamist militants from towns they had seized. But the man who U.S. officials believe designed and built the underwear bombs, Ibrahim Hassan Asiri, remains at large.