WASHINGTON - Pakistani agents arrested Khalid Shaikh Mohammed, suspected of being the mastermind behind the terrorist attacks of Sept. 11, 2001, during a bloodless early morning raid yesterday in a city just outside Islamabad, U.S. and Pakistani officials said.
Although he is hardly a household name in the United States, intelligence and law enforcement authorities say Mohammed is probably the most dangerous al-Qaida operative in the world - and perhaps the most important figure captured since the global manhunt for al-Qaida began after the worst terrorist attacks in U.S. history.
His arrest at 3 a.m. with two other suspected extremists at a safe house in the city of Rawalpindi, which is home to Pakistan's military headquarters, marks a huge victory for the United States in its war on terror, authorities said.
The Associated Press quoted a senior government official as saying that Mohammed was handed over to the United States and taken to an undisclosed location outside Pakistan after being interrogated by Pakistani officials.
No matter where he goes, U.S. officials are expected to keep details about Mohammed's custody and whereabouts a closely guarded secret, as they have with other captured operatives.
The White House commended Pakistan for its help, describing Mohammed's arrest as a joint U.S.-Pakistani operation. One official said the Pakistanis carried out the raid using intelligence from the United States.
"Khalid Shaikh Mohammed is one of Osama bin Laden's most senior and significant lieutenants, a key al-Qaida planner and the mastermind of the Sept. 11 attacks," said White House spokesman Ari Fleischer.
As the spiritual and titular leader of al-Qaida, Osama bin Laden remains the face of terrorism for most Americans and the most prized fugitive for U.S. authorities. But intelligence officials believe the Kuwaiti-born Mohammed played a more vital operational role than bin Laden in orchestrating and executing attacks in the United States and overseas.
Until his capture, the White House said, Mohammed remained "centrally involved in plotting by al-Qaida," including plans "to launch attacks within the United States."
CIA Director George J. Tenet told National Security Adviser Condoleezza Rice about the arrest in a midnight phone call to Camp David, where she was staying with the president and the first lady. Rice then informed the president.
According to the White House, President Bush was ecstatic, saying "That's fantastic."
Top U.S. officials said it was impossible to overestimate the value of Mohammed's arrest.
According to once-classified congressional testimony from Tenet, the U.S.-educated Mohammed, 37, is the "common thread" connecting the first World Trade Center bombing in 1993 to the Sept. 11 attacks.
In addition, officials say privately, his fingerprints are on nearly every major al-Qaida attack in the last decade. Officials suspect that Mohammed was also involved in the bombings of the U.S. Embassies in Kenya and Tanzania in August 1998 and the bombing of the USS Cole in Yemen in October 2000.
His arrest "is pretty damn big - huge - in two respects," said one top U.S. official long involved in the hunt for him.
"First, we're taking out the guy who's responsible for 9/11, and that's huge," said the official, who spoke on the condition that he not be named. "But he [Mohammed] also knows a lot, going backward and forward, about al-Qaida's operations, and that could be valuable if he decides he wants to talk to us."
He said Mohammed probably would be placed in military or CIA custody and remain incommunicado for months or years.
The official said he thinks it highly unlikely that Mohammed would be subjected to the civilian justice system in the United States.
"It'll be a lot better if we can interrogate him for a year and a half without having to worry about telling him in [court papers] everything we know about him," the official said. Federal criminal defendants in the U.S. get access to the government's evidence against them.
Perhaps more than anyone, U.S. counterterrorism officials say, Mohammed's work for al-Qaida epitomized its patience and resilience in planning and executing attacks.
The FBI first came across Mohammed after it tracked down Ramzi Yousef, the mastermind of the 1993 World Trade Center bombing. Yousef, U.S. intelligence officials have said, is Mohammed's nephew.
Although they lack solid proof, American law enforcement officials have long speculated that Mohammed helped plan the 1993 attack, in which Yousef unsuccessfully sought to bring down the twin towers with an explosives-laden van detonated in the center's underground garage.
The only thing they know for sure is that Mohammed wired money to his nephew as the attack plans were being laid in New York, federal law enforcement officials have confirmed.
After the Trade Center bombing, Yousef fled the United States and joined Mohammed in the Philippines, court records show. With a small group of extremists there, the men hatched a scheme in 1995 to simultaneously blow up 12 U.S. passenger planes on cross-Pacific flights. But the plan was foiled.
At the same time, they also struck on another idea: having a suicide pilot fly a plane into CIA headquarters in suburban Washington.
Cam Simpson writes for the Chicago Tribune, a Tribune Publishing newspaper. The New York Times contributed to this article.