President Bush hailed the demise of the 1972 Anti-Ballistic Missile Treaty on Thursday, and urged Congress to develop defense systems to guard against strikes by terrorists now that the ban is lifted. 

"As the events of Sept. 11 made clear, we no longer live in the Cold War world for which the ABM Treaty was designed," Bush said in a statement, choosing not to publicize the treaty's death with a public appearance. 

He took the low-key approach out of sensitivity to Russian President Vladimir Putin, who reluctantly went along with Bush's push to scrap the ABM treaty. Bush gave notice six months ago that the United States would withdraw. The decision took effect Thursday. 

Critics say Bush's missile defense goals are unreliable and expensive. 

Treaty supporters included much of the international community, many U.S. lawmakers and arms control advocates. Until recently, NATO foreign ministers had routinely described the treaty as the "cornerstone of strategic stability," and many Europeans still support it. 

"We now face new threats from terrorists who seek to destroy our civilization by any means available to rogue states armed with weapons of mass destruction and long-range missiles," the president said in a four-paragraph statement. 

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 missile defense system. 

The treaty had banned such construction. 

Urging Congress to approve his missile defense budget, the president said, "I am committed to deploying a missile defense system as soon as possible to protect the American people and our deployed forces against the growing missile threats we face." 

Putin and Bush agreed last month to cooperate on missile defense, including expanding military exercises, sharing early-warning data and exploring potential joint research and development of missile defense technologies.