(Adds Libya was not told in advance, Khatallah aboard the USS New York)
By Phil Stewart and Jeff Mason
WASHINGTON, June 17 (Reuters) - The United States said on Tuesday it had captured a suspected ringleader of the 2012 attack on the U.S. diplomatic compound in Benghazi, Libya, that killed four Americans including the U.S. ambassador and ignited a political firestorm in Washington.
President Barack Obama said in a statement he had authorized the operation in Libya on Sunday, in which U.S. special operations forces captured Ahmed Abu Khatallah. He told an audience later in Pittsburgh that Khatallah was being transported to the United States.
"Since the deadly attacks on our facilities in Benghazi, I have made it a priority to find and bring to justice those responsible for the deaths of four brave Americans," he said in a statement. He said Khatallah would "face the full weight of the American justice system."
Khatallah's capture was a victory for Obama, who has been accused by Republicans of playing down the role of al Qaeda in the 2012 attacks for political reasons and being slow to deliver on promises of justice.
Republicans also said then-Secretary of State Hillary Clinton had failed to take steps to ensure the safety of American diplomatic personnel, an issue that is still resonating as Clinton considers running for U.S. president in 2016.
Clinton defended the decision to put diplomats in dangerous situations on Tuesday but noted that incomplete information increased the risk in Benghazi in 2012.
"We send Americans into perilous dangerous places all the time, and I believe that's the right decision," Clinton told CNN. "We have to do it prudently, of course, but we need to be where things are happening that can affect us."
Khatallah was being held aboard the USS New York, an amphibious transport dock, a U.S. official said, speaking on condition of anonymity.
He was grabbed on the outskirts of Benghazi in an operation carried out by U.S. special operations forces, including some members of the Army's Delta Force, another U.S. official said.
General Martin Dempsey, chairman of the Joint Chiefs of Staff, said U.S. troops had acted with "extraordinary skill, courage and precision" and that the complex operation resulted in no casualties. Rear Admiral John Kirby, the Pentagon press secretary, said all U.S. personnel involved had left Libya.
A U.S. official said Khatallah would be charged and prosecuted through the U.S. court system and would not be sent to the prison for suspected al Qaeda militants in Guantanamo, Cuba.
That is in line with Obama's policy of prosecuting suspected militants caught abroad through the U.S. justice system rather than trying them in the military tribunal system at Guantanamo Bay prison, which he is trying to close.
A criminal complaint released by the U.S. district court for Washington, D.C., accused Khatallah of killing a person in the course of an attack on a federal facility, providing material support to terrorists and using a firearm in commission of a crime of violence.
SPECIAL INTERROGATION TEAM
The Libyan government had no immediate comment on the U.S. announcement. A U.S. official, speaking on condition of anonymity, said Libya was not notified before the secret raid. The Pentagon said Libya had been told of the operation to seize Khatallah but would not say when.
It was the second time the administration has said U.S. special operations forces have gone into Libya to detain a militant. A U.S. Army Delta Force team grabbed al Qaeda suspect Nazih al-Ragye, better known as Abu Anas al-Liby, in Tripoli in October 2013 and sent him to a U.S. Navy ship for interrogation.
Al-Liby was later charged in a U.S. federal court in New York in connection with the 1998 bombing of the U.S. embassy in Kenya, which killed more than 200 people.
Khatallah was expected to be questioned by an elite inter-agency interrogation team created in 2009 to seek information from suspects to prevent future terrorist attacks, a U.S. official said.
The official could not say whether members of the U.S. High Value Detainee Interrogation Group, which is housed at the FBI's National Security Branch, were already in place to question Khatallah aboard the ship where he was being held.
Lawmakers welcomed Khatallah's capture, but Republicans said they were concerned that prosecuting him in the court system rather than through the military tribunals at Guantanamo would hamper efforts to interrogate him for his intelligence value.
"I want him to be held a sufficient period of time under the law of war to gather intelligence," said Senator Lindsey Graham of South Carolina, adding he didn't care where Khatallah was prosecuted. "We're shutting down intelligence-gathering. We're turning the war into a crime, and it will bite us in the butt."
The White House defended the use of the U.S. courts to prosecute Khatallah, saying in a statement that the justice system had "repeatedly proven that it can successfully allow us to gather intelligence, handle the threat we continue to face and prosecute terrorists." (Additional reporting by Patricia Zengerle, Julia Edwards, Missy Ryan and Susan Heavey; Writing by David Alexander; Editing by David Storey, James Dalgleish, Cynthia Osterman and Steve Orlofsky)