Glimmers of hope for survivors from Tuesday's terrorist attacks faded to the grim reality Thursday that thousands of Americans are gone forever.
New York Mayor Rudolph Giuliani reported 4,763 people missing after hijacked jetliners slammed into his city's World Trade Center. That toll came atop the 126 people believed killed in a simultaneous attack at the Pentagon. At least 266 passengers and crew members aboard the four jets also were killed.
President Bush spoke of Tuesday's terrorist attacks in New York and Washington in historical terms.
"We've just seen the first war of the 21st century," he said.
White House officials singled out Osama bin Laden, the Islamic militant who operates from Afghanistan, as a prime suspect in Tuesday's attacks and vowed a comprehensive military campaign to demolish terrorist networks and topple regimes that harbor them.
"It's not just simply a matter of capturing people and holding them accountable," said Paul D. Wolfowitz, deputy secretary of defense, "but removing the sanctuaries, removing the support systems, ending states who sponsor terrorism."
Bin Laden changed locations within Afghanistan just minutes after reports of the attacks, a Pakistani intelligence source said Thursday.
Bin Laden would not tell anyone where he was moving, the source told The Associated Press.
Investigators have evidence that the planning of the suicide hijackings began at least five years ago, and that the men who commandeered two Boston flights began casing Logan Airport at least six months ago, law enforcement sources told The Boston Globe.
The FBI also has evidence suggesting that at least five of the 10 men who hijacked the planes that departed from Boston and plowed them into the World Trade Center exploited the good reputation of the United States' staunchest Arab ally, Saudi Arabia, to gain entry to the country and access to aeronautics training in Florida -- training they used to kill thousands of Americans in the worst act of terrorism in U.S. history.
Late Thursday, Secretary of Defense Donald Rumsfeld recommended calling up members of the reserve, initially to help support the combat air patrols securing the skies over major U.S. cities, Pentagon officials said.
Congress, despite some misgivings from lawmakers over granting Bush open-ended authority, agreed early today to final details of a $40 billion package to combat terrorism and recover from the attacks. The figure was double what President Bush requested.
As emergency workers pursued their solemn mission to find thousands of people missing in the rubble of the World Trade Center in New York and at the Pentagon, the nation remained palpably on edge. Bomb scares and suspicious packages caused the evacuation of the Capitol and buildings in Manhattan. Vice President Dick Cheney was moved to Camp David for security reasons. An armed cordon was established around the executive mansion, with the surrounding area patrolled by police in full riot gear.
The administration took a more aggressive posture Thursday after the shock of the previous two days, making Bush more visible.
"Make no mistake about it, this nation is sad," Bush said in an appearance in the Oval Office Thursday morning. "But we're also tough and resolute, and now's an opportunity to do generations a favor by coming together and whipping terrorism, hunting it down, binding it and holding them accountable."
Secretary of State Colin Powell stated in the strongest terms yet that the administration believed that bin Laden was behind Tuesday's devastating attacks.
Referring to Pakistan, one of the few countries which recognizes the Islamic Taliban who rule Afghanistan, and to Afghanistan itself, Powell said, "When you look at the list of candidates, one resides in that region."
Asked if that candidate was bin Laden, he replied with a curt "Yes."
He said that the administration would present a case to the world against those believed responsible for the carnage in New York and Washington. "We will go after that group, that network, and those who have harbored, supported and aided that network, to rip the network up," Powell said.
As he mapped the start of the anti-terror effort, Powell stepped up the pressure on Pakistan, a nation that has often supported bin Laden, to help the United States bring the accused terrorist to justice. Powell telephoned Pakistan's leader, Gen. Pervez Musharraf, to present him with a list of actions the administration would like him to take.
Sen. Joseph Biden, chairman of the Senate Foreign Relations Committee, met with Gen. Mahmoud Ahmad, the head of Pakistan's intelligence services, who, according to Biden, pledged Pakistan's cooperation.
Another top national security adviser said later in the day that the attacks could have been the work of a number of linked organizations.
"We don't want to be premature," the official said. "We want to be sure we understand all the connections, not just one connection."
Wolfowitz said that the United States and its allies would wage "a campaign, not a single action" to dismantle the terrorist group or groups responsible for this week's attacks, and to bring down the governments that support them.
The administration has asked Congress for an immediate $20 billion to begin building the military and intelligence force required to launch the anti-terror campaign.
"Twenty billion dollars is a lot of money," Wolfowitz said, "but for this country it is a down payment on what we're going to do."
Congress is moving swiftly to approve the funds, although some lawmakers, citing the Gulf of Tonkin resolution and other earlier blank checks written to presidents to conduct undeclared wars, expressed uneasiness about Congress so quickly ceding its constitutional powers to declare war and control the national treasury.
"We want constitutional involvement in the process in which decisions are made," said Rep. David Obey of Wisconsin, a 32-year veteran of Congress who is the senior Democrat on the Appropriations Committee.
Bush, facing a stern test that will recast and define his tenure in office, said that the campaign against terror "is now the focus of my presidency."
He said that he would not neglect domestic concerns. "But now that war has been declared on us, we will lead the world to victory, to victory," he said.
The nascent campaign is being waged on a broad diplomatic front. The administration continued Thursday to try to galvanize an international coalition, its diplomatic and military strategy focused on trying to use Russia and Pakistan in an encircling movement on the north and south of Afghanistan.
Russia has bases in the former Soviet republics of Tajikistan and Uzbekistan and could offer other assets, including intelligence, to the United States for a military assault on bin Laden in Afghanistan.
The planning and the language used by administration officials was read by military analysts as a sign that Powell, the former chairman of the Joint Chiefs of Staff, is preparing the way for a military force that could ultimately be used to occupy Kabul, the Afghan capital, and overthrow the ruling Taliban party.
The Soviet Union occupied Afghanistan from 1979 to 1989, while the United States fought a proxy war, using Mujahideen rebels, against the Soviet troops, who eventually began to withdraw in 1987.
Now, Russia and the United States appeared to be looking for ways to work together against bin Laden in Afghanistan.
Deputy Secretary of State Richard L. Armitage, accompanied by a team of Pentagon and National Security Council officials, is scheduled to meet in Moscow next week with first deputy foreign minister, Vyacheslav Trubnikov. Armitage will be asking the Russians for their detailed knowledge of Afghanistan as well as for access to the Russian military facilities in neighboring Tajikistan and Uzbekistan, administration officials said.
The Russians maintain air bases in those two Central Asian nations, and one of the most crack Russian divisions, the 201st Motorized, operated on the border of Tajikistan and Afghanistan, officials said.
"I'm sure they will be helpful on many things," Powell said of the Russians. "They do have a great deal of experience in Afghanistan and we will draw on all of that experience."
Powell acknowledged that terrorist groups are much harder to find and destroy than conventional states and their armies.
"The kind of organizations that conduct these terrorist activities make for difficult targets," the general said. "It is not as if you're going after an army in the field or you're trying to destroy cities or fixed installations. They're also a thinking enemy."
The New York Times, The Boston Globe and Associated Press contributed to this report.