The arms control deal struck in Italy by President Bush and Russian President Vladimir Putin gives both countries some breathing space on the divisive issue of a U.S. missile shield, and both leaders a summit success to claim back home.

But important policy differences remain between Washington and Moscow, as competing statements made Monday by Bush and Putin helped underscore.

A day after the two agreed to tie missile defense plans to arms-reduction talks, Bush suggested Putin would have "ample time" to consider how the 1972 Anti-Ballistic Missile treaty's ban on missile defenses could be overcome.

But he qualified the time frame, saying he wanted such an agreement sooner rather than later. "Time is of the essence," he told reporters in Rome, suggesting the United States would go ahead on its own with a missile defense shield if too much time elapsed.

Putin, back in Moscow, denied that the Genoa summit brought a "principal breakthrough" in the missile defense dispute. "We confirmed our adherence" to the ABM treaty, he told a meeting of top Cabinet officials.

That, of course, is the very treaty Bush hopes to scrap, or to heavily modify. It expressly bars either Russia or the United States from deploying a nationwide defense against ballistic missiles. Bush considers it a relic of the Cold War, and his administration hopes to develop a shield as soon as 2004. But Russia, many European leaders and congressional Democrats consider it a cornerstone of arms control.

While denying a breakthrough, Putin cited "significant forward movement." Noting that U.S. national security adviser Condoleezza Rice was coming to Moscow this week to kick off talks on the newly linked issues, he said the negotiations should "play their own positive role in resolving these difficult issues."

Rice said her talks with her Russian counterparts would not be formal negotiations, but more like "defense planning talks."

"We don't expect this to be a set of discussions that goes on for a very, very long period of time, taking years to get to what should be a fairly simple matter," said Rice, an expert on Russia.

The United States and Russia are obligated to reduce strategic nuclear weapons to between 3,000 and 3,500 each -- about half current stockpiles -- under a START II agreement that took years to negotiate and remains unratified. Putin says he wants to cut back to 1,500 each.

Those on both sides of the missile defense issue were heartened by the unexpected Putin-Bush agreement, even if it fell short of a true breakthrough.

"The Europeans can give a sigh of relief. Democrats in Congress will have to wait and see before voting on funds. This has the effect of building time into the process and pushing it down the road," said Spurgeon Keeny, director of the private Arms Control Association.

Sen. Joseph Biden, D-Del., chairman of the Senate Foreign Relations Committee and a missile defense skeptic, said the agreement suggested to him that the administration wouldn't abruptly pull out of the ABM treaty so long as the talks were continuing. "And I think that's very good news," he said.

Rep. Curt Weldon, R-Pa., one of Congress' most outspoken missile defense advocates, said Bush and Putin "have struck the right chord." He predicted the new atmosphere of cooperation could lead to larger U.S.-Russian agreements in other areas, including environmental protection, social programs and debt relief.

He said he was untroubled by Putin's comments in Moscow on adherence to the ABM treaty, saying, "That's for home consumption."

Both Bush and Putin were able to reap gains in prestige from their weekend understanding, analysts suggested.

For Bush, it was a chance to demonstrate his ability to make important deals on the world stage. The former Texas governor took the job with little foreign-policy experience and European allies feared his missile defense plan could spark a new arms race with Russia. It also gave Bush a chance to demonstrate that he wasn't espousing a go-it-alone, or unilateralist, foreign policy.

For Putin, the agreement allows him to claim he's still a global player and remind other world leaders that Russia remains a daunting nuclear power. It also gives Putin leverage in holding Bush to his campaign promise of reducing nuclear warheads and, possibly, in limiting the eventual scope of a U.S. missile shield.

Both Bush and Putin "are advantaged by continuing to talk about this," said Sandy Berger, former President Clinton's national security adviser. "They both want to appear reasonable to the rest of the world."

Still, Berger added, "The easiest thing in the world to agree to is to talk. Now comes the hard part."