Bush, in a statement released Tuesday, said the United States would "meet the threats of the 21st century ... by beginning to field missile defense capabilities."

Defense officials expanded on the announcement, saying they want to build 10 new silos at Fort Greely and put a missile in each. The 10 silos would add to the six excavated last summer at Fort Greely, 100 miles southeast of Fairbanks.

The Fort Greely site is part of a North Pacific test bed the Pentagon says is intended to improve its experimentation with missile defense systems. The president's announcement, though, represents formal approval of what defense planners have said they wanted all along--to make the Fort Greely missiles usable in an emergency.

Eric Engman/Daily News-Miner CALL TO ARMS--Crews work Oct. 12 on the Ground-based Midcourse Defense test bed site, top, on Fort Greely. President Bush said Tuesday he will begin deploying a limited system to defend the nation against ballistic missiles by 2004.

Critics said Bush's move to expand and deploy the missile array unwisely deepens the country's commitment to an expensive, technically shaky program that responds to the least likely threat--a nuclear, chemical or biological weapon delivered via intercontinental ballistic missile by a terrorist group or rogue nation.

"Launching it with an ICBM is the least likely method they would use," said Stacey Fritz, coordinator of No Nukes North, a Fairbanks-based group.

Bush administration critics also have said some other countries see the shield as a way for the U.S. to insulate itself from any reaction to its military actions or to military aid it might provide. That perception may provoke countries, such as China, to build up more nuclear weapons to lessen the confidence the U.S. has in the shield's effectiveness. That, in turn, could provoke build-ups by Russia and India, which could have escalating effects elsewhere, according to the theory.

"The worst thing about missile defense is the arms race it will create," said Fritz, who recently finished a master's thesis on the subject at the University of Alaska Fairbanks.

The missile defense system also is pushing the arms race into the traditionally neutral territory of outer space, she said, because, while the system has yet to show any effectiveness against real-world targets, it does have high potential as a method to attack satellites owned by other countries.

However, J.D. Crouch, assistant secretary of defense for international security, said at a Pentagon briefing Tuesday that America needs a defensive system to face the "threats of the 21st century" referred to by Bush--"cyberterrorism, cyber-warfare, weapons of mass destruction and missiles." Traditional reliance on the United States' offensive military power to deter attackers is no longer enough, he said.

"Deterrence is less reliable, although still very important," Crouch said. "And we think this requires a balance of offensive and defensive capabilities ... In accordance with this approach, we're employing this evolutionary approach to develop some missile defense capabilities."

Secretary of Defense Donald Rumsfeld, speaking prior to Crouch, said the U.S. and its allies need to rethink their military strategies.

"In the 21st century, we are finding that there are very few armies, navies or air forces that are owned and operated by nations that are coming at us," Rumsfeld said. "Quite the contrary. We have a whole series of threats with the very lethal weapons in the hands of individuals and networks."

Fritz said there is little evidence that even a "rogue nation" would be likely to attack the United States with such weapons.

And Rep. Ed Markey, D-Mass., issued a news release Tuesday saying the missile defense system won't deter terrorists. "This system is designed to protect against missiles," he said. "It does nothing to protect against dirty bombs, anthrax, chemical agents released in a subway or hijacked planes." "It wastes taxpayer dollars and lulls us into a false sense of security," Markey said.

The Missile Defense Agency has received about $7.8 billion from Congress in the past two budget years, out of a roughly $350-billion annual defense budget. About half of the missile defense money goes to the "ground-based mid-course" system in which Fort Greely and the state-owned launch site on Kodiak Island will be involved.

Lt. Col. Rick Lehner, spokesman for the Missile Defense Agency, said the president's initiative would require another $1.5 billion spread over fiscal years 2004 and 2005.

Not all the additional money would go to the ground-based system at Fort Greely. Lehner said a new silo--with a missile--costs roughly $25 million. The Defense Department issued a news release Tuesday afternoon saying the initial plan is for 16 interceptors at Fort Greely and four at Vandenberg Air Force Base in California by 2005.

The remaining money would buy a variety of components. Another 20 sea-based interceptors would go on Aegis radar-equipped ships.

Patriot missiles would be loaded on aircraft. To help detect enemy missiles, a system of land-, sea-, and space-based sensors would be built.

Those would include an upgraded radar on Shemya Island in the Aleutians, as well as a sea-based X-band radar and upgraded early warning radars in Greenland and the United Kingdom.

Steve Conn, acting executive director of AkPIRG, an Anchorage-based opponent of the missile defense system, questioned how the Bush administration could suddenly declare such a major new focus without a public discussion in Alaska.

"It's despicable public policy," he said.

Lehner, the Missile Defense Agency spokesman, said the military already conducted an environmental impact statement on a much larger, fully operational missile defense installation with 100 interceptors at Fort Greely that was initially proposed during the Clinton administration.