Russia's warming relationship with the United States was apparent Thursday as Secretary of State Colin Powell emerged from a meeting with his counterpart to speak of the substantial progress the two countries have made on a variety of issues the countries are negotiating.

Powell said he and Russian Foreign Minister Igor Ivanov discussed a full range of bilateral and international relations during their half-hour talk and will meet again next weekend at the U.N. General Assembly in New York. 

Powell described his meeting with Ivanov as "very good" and said their delegations are continuing talks.

Powell announced that he will visit Moscow in December following President Bush's November 13 meeting with Russian President Vladimir Putin in Washington.  Defense Secretary Donald Rumsfeld is going to Moscow this weekend in advance of the Bush-Putin summit.

The United States and Russia are trying to reach agreement on reducing their stockpile of nuclear weapons and girding for a defense against missile attack, Condoleezza Rice, Bush's national security adviser, told reporters at the White House Thursday.

"We believe that we understand each other better, that we are making progress," Rice said.

A senior U.S. official said negotiations are in the works on reducing the number of warheads by about two-thirds. The U.S. and Russia both have roughly 6,000 nuclear warheads. The cutback is meant to ease Russia's concerns about U.S. missile defense tests barred by a 1972 Anti Ballistic Missile Treaty with Moscow.

But Rice said that it is premature to discuss a final deal.

"I would caution against any particular deal at any particular time," Rice said.

She stressed the Bush administration would not be able to pinpoint the level of weapons needed until the Pentagon concluded a review. It is very close to conclusion, she said.

"This is not an arms control negotiation in which we try to equalize the number of weapons," Rice said. 

Bush has not yet signed off on any numbers, a senior White House official said.

Rice said the treaty can be amended to allow the administration to test and develop the missile defense system but other officials, including Rumsfeld, want to sack the treaty altogether.

Ivanov's one-day visit to Washington could improve chances for concluding an arms reduction agreement during the summit in two weeks. Ivanov said Thursday that he and Powell had made "substantive" progress on talks and were in the process of finalizing documents to be presented during the meeting.

The two sides are closer to agreement on weapons cutbacks than on missile defense.

Bush plans to erect a shield against attack by smaller states with fledgling missile capabilities and by terrorist groups. Putin is leery of scrapping the 1972 U.S.-Soviet treaty that prohibits a nationwide defense system for either the United States or Russia.

Bush urged Putin to reconsider that view during a meeting in Shanghai last month. He argued that in the face of new terror threats, a missile shield is more critical than ever. But critics say an anti-missile shield will only encourage potential aggressors to develop more dangerous weapons with unorthodox delivery systems to get through the U.S. defense.

The Transportation Department prohibited private planes from flying near the nation's 63 nuclear power plants this week. Government officials are also keeping an eye out for possible smuggling of radioactive materials or dirty nukes being smuggled over the border with Mexico. 

Traditional diplomatic caution keeps American officials from predicting success in Bush's quest for leeway to proceed with a limited defense against missile attack and Putin's hope for substantial reductions in long-range nuclear arsenals.

"We will reach agreements with the Russians on what we can reach agreements on," John Bolton, the undersecretary of state in charge of arms control questions, said Wednesday, ahead of Ivanov's arrival. Bolton has made four trips to Moscow during the administration's first 10 months for talks on U.S. and Russian nuclear weapons.

Bolton and other administration officials are trying not to speculate on the outcome of the meetings, but officials have noticed that Bush and Putin have a personal chemistry that may make negotiations easier.

That relationship was demonstrated before Sept. 11. Since then, Putin has shown great support for the United States. He was the first foreign leader to call on Bush after the terror attacks and has offered to help the U.S.-led coalition's campaign to uproot the Al Qaeda terror network's Afghanistan headquarters.

Russian Defense Minister Sergei Ivanov said Wednesday that regardless of the outcome of the summit or U.S. attacks in Afghanistan, Russia has no plans to alter its participation in the anti-terror coalition.

"Russia has long ago determined its position and its level of participation," he said. That will not change "irrespective of how the operation proceeds," he said.

Last week, Rumsfeld ordered a halt to three missile defense tests that were to take place, saying he didn't want to violate the 1972 pact.

The Associated Press contributed to this report.