The Anti-Ballistic Missile Treaty, long the centerpiece of nuclear equilibrium between the United States and the Soviet Union and a strong deterrent to other nations with nuclear aspirations, is being officially put to rest.

Barring last-minute court intervention, the 1972 ABM treaty expires Thursday, six months after President Bush invoked a provision allowing either side to withdraw upon such notice. It is 30 years and one month old.

Not gravediggers' shovels, but those of construction workers and Pentagon officials will mark the passing of the treaty at a ceremony Saturday in Delta Junction, Alaska, breaking ground on a test site for the administration's $64 billion national missile defense system. The ABM Treaty had banned such construction.

``We have moved beyond an ABM Treaty that prevented us from defending our people and our friends,'' President Bush asserts. The president and his congressional allies claim the treaty — between the United States and a nation that no longer exists, the Soviet Union — outlived its usefulness long ago.

There also are many mourners, among them U.S. allies, lawmakers and arms-control advocates. Until recently, NATO foreign ministers had described the ABM Treaty as the ``cornerstone of strategic stability,'' and many Europeans still support it.

``The ABM Treaty pullout at this stage appears neither prudent nor necessary,'' said Daryl Kimball, executive director of the Arms Control Association. ``Missile defense is an expensive and unreliable method to deal with what is now considered a low-probability threat.''

The treaty ``has served world security well for 30 years,'' said Rep. Dennis Kucinich, D-Ohio, one of 31 House members who filed a federal court suit against Bush on Tuesday in a last-ditch effort to preserve the treaty.

Still, initial anger on the part of some U.S. allies has given way to apparent resignation.

Russian President Vladimir Putin, an outspoken defender of the treaty, relented and signed an agreement with Bush in Moscow last month pledging future missile-defense cooperation.

``The Russians will benefit, we will benefit, the world will benefit. Because this missile defense will basically be aimed at terrorists and rogue states,'' said Rep. Curt Weldon, R-Pa., a longtime missile-defense advocate. ``Civilized nations, and hopefully that will eventually include China, will come together and work on this technology as partners.''

President Nixon signed the ABM treaty with Soviet leader Leonid Brezhnev in the Kremlin in May 1972.

Brezhnev ``used a red pencil to sketch missiles on the notepad in front of him,'' as over a three-day period they negotiated both the ABM Treaty and the companion SALT I pact to limit offensive nuclear weapons, Nixon recalled.

``The ABM Treaty stopped what inevitably would have become a defensive arms race,'' Nixon wrote in his memoirs. ``The other major effect ... was to make permanent the concept of deterrence through `mutual terror.'''

The concept was that both countries had enough missiles to destroy each other many times over, with or without a missile-defense system. Any attack by one thus would amount to joint suicide.

That policy of mutual assured destruction, known as MAD, not only produced superpower stability but also helped discourage other nations from becoming nuclear powers, suggest arms-control analysts.

It provided as well the underpinning for a series of arms-reduction treaties, right up through the one in May in which Bush and Putin pledged to cut their long-range nuclear arsenals by two-thirds, to 1,700-2,200 warheads, over the next decade.

Republicans have made missile defense a high priority since 1983, when President Reagan outlined an ambitious Strategic Defense Initiative that included space-based interceptors. It was ridiculed by critics as ``Star Wars'' and GOP efforts to bring it about withered in a succession of Democratic-controlled Congresses.

The world changed in 1998.

Then, India and Pakistan conducted back-to-back nuclear tests. North Korea tested a surprisingly sophisticated long-range missile. And evidence suggested Iran was working on a similar capability.

President Clinton, under pressure from Republicans, signed legislation in 1999 to deploy a limited missile defense when one was technologically feasible. Near the end of his term he deferred a decision on deployment to the next president.

Bush ran with it, notifying U.S. allies and Russia early in his term that he intended to withdraw from the ABM Treaty and build a missile defense.

Missile defense defenders said the Sept. 11 attacks and subsequent terror alerts only reinforce the need to strengthen defenses and relegate the ABM Treaty to what Sen. Jesse Helms, R-N.C., called ``the dustbin of history.''

But arms-control activist Jonathan Schell of the Nation Institute warns of ``a whole chain of further consequences'' to scrapping the treaty, including putting pressure on China to increase its nuclear arsenal. ``And that sends a bad signal to the whole world,'' he said.