WASHINGTON/NEW YORK - The White House vowed retaliation by a ``mighty giant'' awakened by the world's worst terror acts as investors held their breath on Monday to see how Wall Street would react to the attacks that reduced the World Trade Center to smoking ruins.

The Bush administration pledged to avenge the devastating attacks by hijacked airliners that plowed into the trade center's twin towers and the Pentagon near Washington, but warned the fight could be hard and long. The White House said Islamic zealot Osama bin Laden was the prime suspect.

Those who attacked the United States ``made a terrible mistake ... they have roused a mighty giant,'' President Bush ) told reporters in Washington.

``It's time for us to win the first war of the 21st century so our children and grandchildren can live peacefully.''

U.S. law enforcement agencies hunted for the network behind the attacks which left more than 5,000 dead or missing and destroyed the World Trade Center -- a symbol of American prosperity -- and dealt a heavy blow to the heart of U.S. military power.

As part of the strategy, the White House is considering lifting an executive order banning U.S. involvement in overseas assassinations and Vice President Dick Cheney said the CIA may once again be allowed to recruit agents to conduct ``the mean, nasty, dirty, dangerous business'' of spying on extremists.

While Washington rattled its saber, a delegation from Pakistan took the first steps to head off a military crisis by meeting with neighboring Afghanistan on Monday to press the ruling Taliban to hand over bin Laden, who has lived for years
in the Islamic nation.

Foreign Minister Abdul Sattar, speaking as the delegation arrived in Afghanistan, said that any decision to hand over bin Laden lay with the Taliban themselves. The delegation would urge the Taliban ``to act responsibly in the terribly grave situation,'' he told CNN.

As Bush rallied a global coalition for war against the ''barbarians'' who staged the attacks, the president heard encouraging sounds of support from European allies but also heard some notes of fretful caution.

``Every country, including all in ASEAN (the Association of South East Asian Nations), would like to see the United States obtain clear-cut evidence and a thorough investigation before starting its operations,'' Thai Foreign Minister Surakiart Sathirathai told reporters ``Don't jump the gun now on what and how the U.S. will respond.''

On Wall Street, grief matched by resolve

The cost of the attacks will be colossal and with investors holding their breath for Wall Street to open, the government signaled it was ready to provide economic props to try and keep the United States from sliding deeper into a downturn.
The grief of mourning Wall Street financiers was matched by their resolve to get back to business as usual.

Just three blocks southeast of where the towers collapsed, a giant U.S. flag fluttered above the entrance to the New York Stock Exchange ready for the thousands of people expected to return on Monday morning for the opening bell.

``You're damn right the firm is going to come back,'' said David Komansky, chairman and chief executive of America's powerful brokerage Merrill Lynch and Co. ``This place did not get to be what it is by having a bunch of pussycats here.''

The NYSE, the world's largest stock exchange, has been closed, along with other New York financial markets, since Tuesday, the longest shutdown since the Great Depression.

In a symbolically charged ceremony, representatives of New York's police and fire departments will ring the NYSE's opening bell at 9:33 a.m. EDT after two minutes of silence to honor the victims and the singing of ``God Bless America.''

In a harbinger of what may come, Tokyo stocks hit a 17-year low on Monday. The benchmark Nikkei average fell 5.04 percent to close at 9,504.41, the lowest since December 1984.

``I have great faith in the resiliency of the economy,'' Bush said. ``The markets open tomorrow ... We'll show the world.''

In a show of confidence, U.S. billionaire investor Warren Buffett, whose views on the market are followed closely by the financial world, said on Sunday he would not sell stocks when the market reopened and might be a buyer.
Chilling search, poignant moments
Weary rescue workers labored for a seventh day over the smoldering World Trade Center ruins in the heart of New York's financial district, but prospects dimmed that any of the nearly 4,957 people now listed as missing in the concrete and steel sarcophagus survived.

In a chilling discovery, the body of a male air crew member was found bound hand and foot, a police source said. Earlier, the body of a flight attendant was found with her hands bound.

Away from the site, thousands of posters of those missing covered bus shelters, telephone booths and subway walls.

One, poignant in its simplicity, read: ``Have you seen my Daddy? Jason Jacobs.'' It carried a telephone number and a photograph of a smiling toddler playing with her father.
In the most recent count, 190 people were confirmed dead, including 37 firefighters and rescue workers.

Across New York, mourners struggling to make sense of the carnage packed churches for memorial services and flocked to firehouses to pay tribute to ``New York's Bravest.''

More than 300 firefighters and emergency service workers are among the missing. ``The worst part is when you come across bunker gear, and you know you've got a firefighter. It's horrendous. They pulled my chief out yesterday,'' firefighter Joseph Tustin said.

In Tuesday's attacks two hijacked airliners struck the World Trade Center, another the Pentagon and a fourth crashed into a Pennsylvania field.

As more details emerged of the nightmarish day, Cheney said Bush had made the ``horrendous'' decision to shoot down civilian airliners if they threatened the Capitol or the White House.

Hundreds attended a memorial for 31-year-old Jeremy Glick in the upstate New York resort of Windham on Sunday. He was one of four passengers who apparently overpowered hijackers causing one plane, bound for Washington, to crash in Pennsylvania.

Glick had called his wife, Lyzbeth, by cellular telephone from the doomed airliner shortly before it crashed and had told her: ``We're going to rush the hijackers.''

``In the darkness of last Tuesday, Jeremy Logan Glick was a light,'' Rep. John Sweeney New York Republican, told mourners.

Massive hunt, Bin Laden Prime suspect

The FBI has 4,000 agents tracking 40,000 leads.

U.S. officials said on Sunday that two more ``material witnesses'' had been taken into custody, joining two others already detained. Such witnesses are usually considered important enough to affect the outcome of a case.

A further 25 people were taken into custody on alleged immigration violations and were being questioned, and the FBI was seeking more than 100 others for questioning.

Investigators hoped the arrests and detentions would eventually lead them to the man the White House said with growing conviction was their prime suspect -- Osama bin Laden.

Bin Laden, a 44-year-old multimillionaire militant, denied in a statement that he conducted the attacks, saying that Afghanistan would not permit it. He is believed to be responsible for previous attacks on the U.S. in retribution for ''desecration'' by U.S. troops during the 1990-91 Gulf crisis.

Cheney was not buying bin Laden's denial. ``We are quite confident ... that he is in fact the prime suspect,'' he said.

Cheney, Defense Secretary Donald Rumsfeld, Secretary of State Colin Powell and other officials stressed that there were more people and groups involved than just bin Laden.
Rumsfeld said on ABC's ``This Week'' the battle would take years. ``It will be political, economic, diplomatic, military.''

A small advance took place on the diplomatic front when Pakistan's military ruler, Gen. Pervez Musharraf, pledged full cooperation with the United States.

Powell expressed cautious optimism that condemnations by Iran and Syria of Tuesday's attacks could open the door to cooperation with two unlikely allies.

In Kabul, the spiritual leader of the Taliban, Mullah Mohammad Omar, called an urgent council of Islamic clerics to discuss the defense of his increasingly isolated nation.

Witnesses said on Monday that Taliban officials were fleeing Kabul amid expectations of U.S. attacks. Officials and their families were heading for the countryside but it was not clear if this was under instruction from their leader.