WASHINGTON - President Clinton said Friday he is not convinced the technology is at hand to build an effective anti-missile shield and will leave it to the next president - Al Gore or George W. Bush - to decide when, or if, to deploy a national missile defense that is prohibited by a 1972 arms control treaty.
''We should not move forward until we have absolute confidence that the system will work,'' Clinton said in a speech at Georgetown University explaining why he believes it is too early to commit the United States to missile defense. He ordered the Pentagon to pursue a ''robust program'' to prove the effectiveness of the technology.
In response, Bush reiterated that if elected he would deploy a missile defense ''at the earliest possible date.'' He characterized Clinton's decision as evidence of failed leadership on national security issues.
Bush did not say what kind of missile defense he would advocate, but in the past he has said he favored a system that could defend not only the United States but also its allies - an approach that the Clinton administration and many private defense experts say would take longer to bear fruit than Clinton's approach.
Gore welcomed Clinton's decision as providing needed time to more thoroughly test the technologies.
''I welcome the opportunity to be more certain that these technologies actually work together properly,'' Gore said.
The upshot of Clinton's decision is that the Pentagon's 2005 target date for having an initial, limited means of defending all 50 states against attack by a small number of ballistic missiles has been scrapped.
To maintain that schedule, Clinton would have had to authorize the Pentagon - before the end of this year - to award contracts for initial construction on Alaska's Shemya Island of a powerful new radar that would provide the missile-tracking capability needed for an effective missile defense.
Clinton's decision likely means that work on the Shemya radar cannot begin before 2002, which means that a national missile defense could not be completed before 2006 at the earliest. The decision gives the next president leeway to restructure the program or reorder its priorities.
The decision also appeared to please the Russian government, which, along with China, has led the international opposition to a U.S. missile defense. They argue that it would upset the international strategic balance by placing in jeopardy the deterrent effect of their own arsenals of offensive nuclear missiles.
In Moscow, Gen. Leonid Ivashov, a senior Defense Ministry official who has been among the harshest critics on this issue, was quoted by the Interfax news agency as saying Clinton's decision showed ''elements of constructiveness.''
The Clinton administration has tried, unsuccessfully, to persuade the Russians to amend the 1972 Anti-Ballistic Missile treaty, which explicitly forbids a nationwide defense against long-range ballistic missiles. The treaty allows either party to withdraw from its provisions after providing six-months notice.
On Capitol Hill, the House's most vocal supporter of national missile defense, Rep. Curt Weldon, R-Pa., said Clinton chose to ''beg our allies and our enemies for permission to move ahead with missile defense.''
Another Republican, Sen. Chuck Hagel of Nebraska, said Clinton made the right decision.
''There will be dangerous consequences for America and the world if we rush to meet arbitrary decision deadlines,'' Hagel said.
Congress last year passed a law requiring deployment of a national missile defense as soon as ''technologically feasible'' - leaving open to debate when the technology is mature enough to build a reliable defense. Clinton also took into consideration the cost, the level of threat of missile attack and the international implications, including the impact on relations with Russian and European allies.
Defense Secretary William Cohen, a Republican and perhaps the administration's strongest advocate of national missile defense, issued a statement supporting Clinton's decision.
''The president's statement today underscores the importance of having the next president fully involved in decisions regarding the future of the program before committing the United States to a deployment strategy,'' Cohen said.
In his speech, Clinton credited the Pentagon with overcoming ''daunting technical obstacles'' in the developing of missile defenses. But he made clear he believes more testing is needed to validate the technology.
Clinton noted that the last two flight tests of the proposed missile interceptor have failed to hit their targets, and that questions remain about ''countermeasures,'' or methods of defeating a national missile defense, or NMD.
''I simply cannot conclude, with the information I have today, that we have enough confidence in the technology and the operational effectiveness of the entire NMD system to move forward to deployment,'' he said.
