WASHINGTON — Vowing not to be cowed, President Bush pledged a crusade against terrorists Sunday as top administration officials zeroed in on Saudi exile Osama bin Laden and Afghanistan's Taliban militia for possible retribution for last week's terrorist attacks.

"No question, he is the prime suspect. No question about that," Bush said, brushing off a reported denial of responsibility by bin Laden.

As Bush sought to rally Americans to get on with their lives and jobs, administration officials asserted on the Sunday talk shows that nations that harbor terrorists would face the "full wrath" of the United States.

They emphasized that the battle against terrorism would be long and include legal, diplomatic and economic offensives as well as military action.

Vice President Dick Cheney disclosed that after suicide hijackers slammed planes into the World Trade Center in New York and the Pentagon on Tuesday morning, Bush ordered the military to shoot down any commercial aircraft that disobeyed orders to turn away from Washington's restricted air space.

Bush, upon returning to the White House from Camp David, said: "I gave our military the orders necessary to protect Americans. Of course, that was difficult."

Bush, who was in Florida at the time of the attacks, added: "Never did I dream we would be under attack this way."

The president also said that the nation and its limping economy were resilient and would bounce back.

"Tomorrow when you get back to work, work hard like you always have." he told Americans. "My administration has a job to do. … We will rid the world of evildoers."

"This crusade, this war on terrorism, is going to take awhile. And American people must be patient," Bush said.

Cheney, appearing on NBC's "Meet the Press," had harsh words for Afghanistan, where bin Laden has operated since 1996, and the Taliban, the Muslim fundamentalist militia that controls most of Afghanistan.

"The government of Afghanistan has to understand that we believe they have, indeed, been harboring a man who committed and whose organization committed this most egregious act," Cheney said. "They have to understand, and others like them around the world have to understand, that if you provided sanctuary to terrorists, you face the full wrath of the United States of America."

Secretary of State Colin Powell used the same "full wrath" language in his TV appearances. Powell said the Taliban faces a simple choice: Deliver bin Laden or face near-certain retaliation.

On Sunday morning, Bush worshipped at the Camp David chapel, joining millions of Americans who went to church seeking comfort in prayers five days after the devastating attacks.

"America the Beautiful" rang out from church organs across the country, and small American flags were held with prayerbooks.

By Sunday, 180 were confirmed dead at the World Trade Center ruins; the number of missing was 5,097. In the Pentagon attack, 188 were believed dead.

Authorities have thus far arrested two men in connection with the terrorist acts, and detained 25 people in the investigation for possible immigration violations.

More of the roof of the fire-damaged Pentagon collapsed early Sunday morning, creating a small landslide of debris as workers tried to push further into the building. In New York, Mayor Rudolph Giuliani said reports of tapping from the wreckage of the World Trade Towers were unfounded and that no signs of life had been detected.

Meanwhile, the United States turned to Pakistan as a potential ally in hunting down bin Laden. Pakistan sent senior officials to Afghanistan to warn the Taliban that it faces a massive assault if it does not hand over the fugitive to the United States, a top Pakistani official said, speaking on condition of anonymity.

Bin Laden has been indicted in the 1998 bombing of two U.S. embassies in east Africa and linked to the 1993 World Trade Center bombing.

Bush spoke by phone to Pakistani President Gen. Pervez Musharraf on Saturday. "The leader of Pakistan has been very cooperative," Bush said Sunday. He also spoke with Indian Prime Minister Atal Bihari Vajpayee on Sunday, aides said.

Attorney General John Ashcroft, meanwhile, said he would ask Congress for new authority to make it easier to track down and prosecute terrorists, including expanded wire tap authority. "We need additional tools to stop the kind of tragedy that happened," Ashcroft said.

Transportation Secretary Norman Y. Mineta announced a task force of experts to report back by Oct. 1 on ways to increase airport and airplane security, particularly the security of cockpits. He also said all oil and natural gas pipeline operators had been directed "to take steps to implement security measures."

The nation began a return to normalcy. Professional baseball games were to resume Monday and the stock markets were to reopen.

"No question about it, this incident affected our economy, but the markets open tomorrow; people go back to work. And we'll show the world," Bush said.

Cheney made clear that the United States considered bin Laden the main suspect.

"What we are going to do is aggressively go after Mr. bin Laden, obviously, and all of his associates, and even if it takes a long time, I'm convinced eventually we'll prevail," Cheney said. "I have no doubt that he and his organization played a significant role in this."

Defense Secretary Donald H. Rumsfeld said bin Laden is only part of the problem, and that the campaign of terror is "much bigger than one person."

"It's a matter of his network," Rumsfeld said on "Fox News Sunday." "If he were not there, there'd be 15 or 20 or 30 other people who would step in. … Obviously, he's a prime suspect, but we have to be realistic."