Washington As a grim precaution, President Bush has created a "shadow government" of 75 or more officials who live and work in mountainside bunkers outside Washington in case nuclear-armed terrorists strike the nation's capital.
"This is serious business," Bush said Friday of a Cold War-era plan that took effect in the hours after the Sept. 11 suicide hijackings.
The top-secret effort, disclosed by government officials who spoke on condition of anonymity, has been retooled since the attacks to protect the continuity of government against the 21st-century threat of terrorism. A major force behind the effort has been Vice President Dick Cheney, who could succeed Bush and oversee the underground government in a calamity.
In a separate precautionary strategy, at least one member of Bush's Cabinet is to be outside Washington at all times.
Congress' plan: to gather at a Washington-area hotel and a nearby military base if disaster strikes the Capitol.
Bush is concerned the al-Qaida network might obtain a nuclear weapon, aides said.
"We take the continuity-of-government issue seriously because our nation was under attack. And I still take the threats we receive from al-Qaida killers and terrorists very seriously," the president said during a trip to Iowa.
U.S. intelligence has no specific knowledge that the network has a nuclear weapon, officials said.
Without confirming details of the doomsday plan, Bush said, "Until this country has routed out terrorists wherever they try to hide, we're not safe."
Under the classified "Continuity of Operations Plan," 75 to 150 senior government officials Â drawn from every Cabinet department and some independent agencies Â work out of two fortified locations along the East Coast.
They rotate in and out, prohibited from telling anybody where they are or why. Friends, family and co-workers can reach them through a toll-free number and personal extensions.
According to two administration officials who have visited one of the secure sites, the facility is a large bare-bones office space buried deep beneath a mountain.
Sectioned off into executive branch agencies, the bunker is equipped with generators, telephones, television sets, command centers, a few private offices and computers.
In an unsettling reminder of the stakes involved, the hallways are lined with food rations.
The project is an extension of a policy that has kept Cheney moving in and out of public view.
In the worst case scenario, the shadow government would help Cheney manage America's affairs after a crippling strike on Washington and the presidency. Bush aides said Cheney helped shape the project by drawing on his experience in government during the Cold War, when the U.S. made contingency plans for a nuclear strike from the Soviet Union.
"I have an obligation as the president, and my administration has an obligation to the American people to ... put measures in place that, should somebody be successful in attacking Washington, D.C., there's an ongoing government," Bush said.
The Washington Post, which first disclosed the catastrophe plan, reported that the typical rotation is 90 days.
Several White House officials have taken a turn at the bunker, spending several nights at a time in the rotation. Most are midlevel aides.
Senior advisers such as chief of staff Andrew Card, National Security Adviser Condoleezza Rice and Counselor Karen Hughes are exempt from the rotation, presumably because they would be with Bush or in a White House bunker.
"You don't talk much about this around here," Hughes said with a chuckle.
Deputy chief of staff Joe Hagin is the White House's point man at the secret sites, spending more time in the bunkers than the West Wing.
The Pentagon also rotates top military officials to secure locations. "We move people around," spokeswoman Victoria Clarke said.
A few hours after the terrorist attacks at the World Trade Center and the Pentagon, five military helicopters settled into a hidden landing pad at a Pennsylvania mountain site. Other military personnel arrived in tan buses to Site R, the hollowed-out granite mountain shelter built in the early 1950s to withstand a nuclear attack.
Local residents call the top-secret site "Little Pentagon."
Immediately after the attacks, one Cabinet member was kept at one of the secure bunkers at all times. Lately, the anointed Cabinet member has been allowed to travel away from Washington Â with increased security Â for business or personal trips.
The third branch of government, the federal court system, is developing its emergency plan.
Bush's plan gelled in December when he issued an executive order that lists Â in their precise line of succession Â the top half dozen or so officials who would take over if a government agency's hierarchy was dismantled. Those officials are in the bunker rotation.