U.S. Special Operations forces have captured Ahmed Abu Khattala, an alleged ringleader of the 2012 attacks on the U.S. diplomatic compound in Benghazi, Libya. Here is what is known about Abu Khattala. (The Washington Post)

Ahmed Abu Khattala had returned home Sunday night after a day of militia skirmishes in Benghazi when U.S. military commandos swarmed his residence south of the waterfront city and took him captive, quickly moving him out of Libya to a U.S. warship.

“He was isolated,” a U.S. official said. “It was pretty clean.”

One of the suspected ringleaders of the 2012 terrorist attacks in Benghazi that killed four Americans, Abu Khattala is the first of the alleged perpetrators to be apprehended. He now awaits a transfer to the United States and a federal trial in the District.

U.S. officials said the joint Special Operations and FBI mission had been planned for months and was approved by President Obama on Friday. The Pentagon said that there were no civilian or other casualties and that all involved U.S. personnel had safely left Libya.

The administration provided few details about the operation itself, where Abu Khattala is being held or the timing of his first appearance in court. After news of the capture became public Tuesday morning, Obama, on a visit to Pennsylvania, said Abu Khattala “is now being transported back to the United States.” Administration officials said they expected him to appear in court here within days.

Obama praised the commandos, said by one U.S. official to be special operators from the Army’s Delta Force, for “showing incredible courage and precision” in capturing the man who “is alleged to have been one of the masterminds” of the Benghazi attacks.

“It’s important for us to send a message to the world that when Americans are attacked, no matter how long it takes, we will find those responsible, and we will bring them to justice,” Obama said.

Abu Khattala’s capture was a significant breakthrough for the administration in a case that has dragged on for nearly two years since Obama promised shortly after the attacks that the perpetrators would be brought to justice.

Response to the capture quickly divided along partisan lines, with Republicans demanding that Abu Khattala be thoroughly interrogated at sea and then brought to the U.S. military prison at Guantanamo Bay in Cuba for a military trial. Democrats argued, along with the administration, that he belongs in criminal court, where convictions against numerous terrorism defendants have been won in recent years.

“The administration’s policy is clear on this issue,” said National Security Council spokeswoman Caitlin Hayden. “We have not added a single person to the [Guantanamo] population since President Obama took office, and we have had substantial success delivering swift justice to terrorists throughout our federal court system.”

Hayden declined to specify the nature of Abu Khattala’s debriefing, but noted that “as a general rule, we will always seek to elicit all the actionable intelligence and information we can from terrorist suspects taken into our custody.”

In 2011, Somali citizen Ahmed Abdulkadir Warsama was picked up off the Somalia coast, held at sea and interrogated for months before being advised of his rights to silence and to counsel. Once brought to this country, he pleaded guilty in federal court to a range of charges, including providing material support for al-Qaeda in the Arabian Peninsula.

(The Washington Post)

In October, Nazih Abdul-Hamed al-Ruqai, also known as Abu Anas al-Libi, was captured in Tripoli, the Libyan capital, in a raid by Delta Force operators and the FBI’s elite Hostage Rescue Team. Briefly detained at sea until he fell ill and was brought to the United States for treatment, Ruqai is awaiting trial in New York, accused of involvement in the 1998 al-Qaeda bombings of two U.S. embassies in East Africa.

A three-count criminal complaint filed by the FBI last July and unsealed in federal court in the District on Tuesday charges Abu Khattala with “killing a person in the course of an attack on a federal facility involving use of a firearm” on Sept. 11 and 12, 2012, providing and conspiring to “provide material support to terrorists resulting in a death” and possessing and using a firearm during a crime of violence.

Conviction on the felony counts could make him eligible for the death penalty or life imprisonment. In a statement, Attorney General Eric H. Holder Jr. said the Justice Department could bring more charges against Abu Khattala.

At least a dozen others are known to have been charged in sealed criminal complaints in connection with the Benghazi attacks, although none of the others have been apprehended.

While the specific timing and location of Abu Khattala’s initial court appearance in Washington was not immediately known, past cases involving high-profile defendants have been held in the U.S. District Court’s high-security courtroom on the fourth floor, equipped with a wall of bullet-resistant glass between the gallery and the well.

A spokesman for the U.S. Marshals Service did not immediately respond to questions about where Abu Khattala will be detained. High-profile suspects in terrorism cases in the past have been held at the D.C. jail.

The State Department designated Abu Khattala a terrorist in January, calling him a “senior leader” of the Benghazi branch of the militant organization Ansar al-Sharia, a group that arose after the 2011 fall of the Libyan regime of Moammar Gaddafi.

Ansar al-Sharia was also designated a terrorist organization and held specifically responsible for the Sept. 11, 2012, assault on the U.S. diplomatic compound in Benghazi that left U.S. Ambassador J. Christopher Stevens and State Department information management officer Sean Smith dead.

Two CIA contractors, Tyrone S. Woods and Glen Doherty, were killed early the next day in a mortar attack at a nearby CIA annex where the attackers moved after overrunning the diplomatic compound.

Believed to be in his 40s, Abu Khattala was imprisoned for many years for his Islamist views by the Gaddafi regime. After Gaddafi was ousted in 2011 by Libyan fighters aided by U.S. and NATO warplanes and subsequently killed by militiamen, Abu Khattala helped form Ansar al-Sharia..

Abu Khattala’s residence is a relatively modest, two-story house in the neighborhood of al-Lathi in southern Benghazi, with no armed guards posted outside.

One former Islamist fighter close to Ansar al-Sharia said Monday that Abu Khattala was frequently on the move, had been “unavailable” for weeks and was not answering his phone.

Neighbors in al-Lathi said they had last seen him Sunday night around sunset, when he returned from fighting in Ansar al-Sharia skirmishes with the forces of Gen. Khalifa Hifter. Hifter has declared war against Islamists in eastern Libya and has been carrying out airstrikes against them for weeks.

That night, Abu Khattala looked tired, said neighbors who did not want to be identified.

The Washington Post learned about Abu Khattala’s capture Monday but agreed to a request from the White House to delay publication of a story because of security concerns. After publication Tuesday morning, administration officials, prior to making a public announcement, notified the families of the Americans who were killed in the 2012 Benghazi attacks.

“It wasn’t something we were expecting,” Doherty’s sister, Kate Quigley, said in a telephone interview. “So much time has gone by.” Quigley said the families had remained in touch with each other.

The administration — which has come under criticism for failing to inform Congress in advance of previous operations, including the May 31 prisoner swap for Army Sgt. Bowe Bergdahl in Afghanistan — told senior lawmakers of the planned Libya operation some days ago, according to Sen. Saxby Chambliss (R-Ga.), the ranking Republican on the Senate Intelligence Committee.

But senior administration officials, speaking on the condition of anonymity, said that they had not informed the Libyan government until after the operation was completed and that it was “a unilateral U.S. operation.”

In October, the administration notified the Libyans prior to the raid in which Ruqai was captured. But violent reaction to that operation led to postponement of plans to capture Abu Khattala days later. At the time, it led to deep frustration within the FBI, which thought it had perhaps lost its best chance to apprehend him.

This time, with Libya still in a state of turmoil, a decision was made not to tell the government in advance. “We have made clear to successive Libyan governments our intention to bring to justice the perpetrators of the attack on our facilities in Benghazi,” one official said. “So it should come as no surprise to the Libyan government that we would take advantage of an opportunity to bring Abu Khattala to face justice.”

Within weeks of the 2012 attacks, and sporadically thereafter, Abu Khattala was interviewed by American reporters in the open in Benghazi, where he said he did not participate in the initial assault on the Benghazi compound but came on the scene as it was ending. The interviews fueled Republican criticism that the administration was dragging its feet in the investigation.

Officials responded sharply Tuesday to questions about the time it had taken to apprehend Abu Khattala. “Look, terrorists go to great lengths to evade capture,” said the Pentagon press secretary, Rear Adm. John Kirby. “What matters is not that it took a matter of time to get him but that we got him.”

This story has been updated to clarify a quotation, attributed to National Security Council spokesperson Caitlin Hayden, about the debriefing of terrorism suspects.

Erin Cunningham and Nizar Sarieldin in Tripoli and Ann Marimow, Ed O’Keefe, Juliet Eilperin and Thomas Gibbons-Neff in Washington contributed to this report.