WASHINGTON - As they began yesterday to interrogate Khalid Shaikh Mohammed, the suspected mastermind of the Sept. 11 attacks who was captured in Pakistan over the weekend, U.S. officials expressed confidence that he could lead them to other al-Qaida operatives within days.
Intelligence analysts have gleaned crucial information from computers and documents in the house where Mohammed was captured Saturday by Pakistani authorities, a Bush administration official said.
"This was the mother lode," the official said, speaking on condition of anonymity.
Mohammed is being held at an undisclosed location outside the United States, officials said.
Privately, FBI and CIA officials reveled in the success of the operation. But they were careful to keep a low profile so as not to alert any new targets that they might be closing in. They said other terrorists are likely to alter plans or move to avoid capture. Intelligence officials thus intend to move quickly on any information they get from Mohammed.
The intelligence agencies are under pressure from senior Bush administration officials not to draw undue attention to the U.S. authorities who were in Pakistan to take Mohammed into custody. Pakistan's government has come under harsh criticism from Islamic extremists for aiding the United States in efforts to dismantle al-Qaida and for allowing the FBI and CIA into the country.
Mohammed's capture came as an enormous boost for President Bush in his effort to show that the nation can aggressively fight terrorism even as it moves to disarm and topple Saddam Hussein's regime in Iraq.
The arrest came as Americans had been expressing diminished confidence in the nation's ability to defeat al-Qaida, which carried out the Sept. 11 attacks and is thought to be planning future strikes against the United States. Democrats and other critics have complained that Bush has allocated too much attention and resources to preparing for an invasion of Iraq at the expense of the war on terrorism.
The capture of Mohammed - one of the FBI's most wanted terrorists - dealt a major setback to al-Qaida's organization. As its operations chief, Mohammed is thought to possess more tactical knowledge than any other operative. U.S. officials hope he can offer details of attacks being planned, especially within U.S. borders, and perhaps offer clues to Osama bin Laden's whereabouts.
"The war on terrorism is succeeding," said Sen. Pat Roberts, the Kansas Republican who chairs the Senate intelligence committee. Appearing on Fox News Sunday, Roberts called Mohammed "the kingfish" and suggested that bin Laden and his second in command, Ayman al-Zawahiri, could be hiding in a lawless area along the Pakistan-Afghanistan border, where Mohammed reportedly spent time.
"If there was one person that we wanted to get, it was this man," Roberts said. "We got the operations manager - more coming. Look out, al-Qaida."
A White House official, asked whether the president believed that Mohammed's capture would silence Democratic critics, said bluntly: "Results speak for themselves."
The president, who on Saturday described Mohammed's capture as "fantastic," offered no public comments yesterday about the arrest or about Iraq as he returned from the Camp David retreat in Maryland's Catoctin Mountains. Bush is entering a crucial two weeks as he tries to sway more Americans - and more members of the United Nations Security Council - to support military action to oust Hussein.
Even as Bush celebrated Mohammed's capture, his administration grappled with a severe setback to its plans for an invasion of Iraq: the refusal by Turkey's parliament to allow about 62,000 American troops to use Turkish soil to launch an attack.
U.S. military commanders had hoped to open a front from Turkey to secure oil fields in northern Iraq, resupply U.S. forces and prevent outbreaks of fighting in the predominantly Kurdish territory. As Secretary of State Colin L. Powell spoke by phone with Prime Minister Abdullah Gul, U.S. officials expressed hope that Turkey's parliament would hold a new vote this week and reverse the decision it took Saturday.
For Bush, a pressing challenge is to convince Americans that he has enough international backing for an Iraq war. Though opinion polls show that more than 60 percent of Americans generally favor military action, most say they would back a war only if the United States has significant support from its allies.
Andrew Kohut, an independent pollster who heads the Pew Research Center, suggested yesterday that Mohammed's capture would show Americans that Iraq isn't the only urgent priority for Bush. Polls indicate that Americans have been losing faith in winning the war on terror as they have seen Bush increasingly focus on Iraq, though they do not generally blame the president.
A recent Pew poll showed that 67 percent of Americans still approve of Bush's handling of the war on terror, higher marks than on any other issue. Kohut said the Mohammed capture would help Bush maintain that level of confidence.
"The war on terrorism has been off the public's radar screen because of Iraq, and this was a shot in the arm," Kohut said. "Bush's approval ratings are really held up by views on how he deals with the war on terrorism. If that 67 percent were to begin to come down, it would be bad for him."
Sen. Joseph R. Biden Jr. of Delaware, the top Democrat on the Senate Foreign Relations Committee, cautioned that the seizing of Mohammed should not be taken as proof that Bush has devoted enough attention and resources to terrorism.
"He has been living in plain daylight" along the Afghan- Pakistan border, Biden said of Mohammed. "And there is overwhelming reason to believe that the other 22 of the 25 top [al-Qaida] officials we're looking for, including bin Laden, are in the vicinity."
Biden, appearing on the Fox network, argued that many others could have been captured had Bush focused the military's efforts more intently on finding terrorists. "How much would that have changed the dynamic," Biden asked, "and our ability to shut down all of al-Qaida?"
U.S. authorities have sought Mohammed for years, even before the Sept. 11 attacks. They had connected him to several plots, including one to crash a plane into CIA headquarters and another to blow up U.S. jetliners around the world.
In previously classified testimony before Congress in June, George J. Tenet, the director of central intelligence, said Mohammed was also connected to the 1993 World Trade Center bombing.
Since the Sept. 11 attacks, Mohammed has tried to restore al-Qaida's organizational structure, which was fractured by the war in Afghanistan, and has also tried to hatch new attacks, U.S. authorities said.
With the Bush administration moving toward war, the U.N. Security Council is expected to vote within two weeks on a U.S.-backed resolution that says Hussein missed his final chance to disarm and authorizes military action. Still, Bush has insisted that he needs no further U.N. authorization to invade Iraq, despite overwhelming opposition to such a war from around the world.
Powell phoned Security Council members yesterday in an intensive lobbying effort to gain support for the resolution.
The Bush administration hopes to put the resolution to a council vote soon after Hans Blix, one of the chief U.N. weapons inspectors, reports to the council Friday on Iraq's compliance with U.N. mandates.
Sun staff writer Mark Matthews and the Associated Press contributed to this article.