MOSCOW - Secretary of State Condoleezza Rice said yesterday that there was no "new Cold War" between Washington and Moscow, although she acknowledged growing strains ahead of contentious talks with Russian President Vladimir V. Putin.

"It's time for intensive diplomacy," said Rice, who will meet with Putin today amid major differences over U.S. missile-defense plans and Putin's increasing criticism of American policy.

Rice said Washington was committed to working through the differences, notably over U.S. plans for a missile-defense system in Europe, Russia's threat to suspend a major military treaty, and Moscow's opposition to a U.N. plan for Kosovo independence.

There is also growing U.S. concern about Moscow's treatment of its former Soviet neighbors and steps Putin has taken to consolidate power in the Kremlin - seen as democratic backsliding as Russia prepares for presidential and parliamentary elections next year.

"I don't throw around terms like new Cold War," Rice said. "It is a big, complicated relationship, but it is not one that is anything like the implacable hostility" between the United States and the Soviet Union for a half-century after World War II.

"It is not an easy time in the relationship, but it is also not, I think, a time in which cataclysmic things are affecting the relationship or catastrophic things are happening in the relationship," Rice told reporters aboard her plane on the way to Moscow.

"It is critically important to use this time to enhance those things that are going well and to work on those things that are not going well."

She noted that the United States and Russia were working together in numerous areas: on Iran and North Korea's nuclear programs, the global spread of weapons of mass destruction, and efforts to achieve Middle East peace.

"Russia is not the Soviet Union, so this is not a U.S.-Soviet relationship, this is a U.S.-Russian relationship," said Rice, an expert on the Cold War who first visited Moscow in 1979.

Her visit comes as the two nations have traded increasingly sharp barbs, despite ostensibly warm personal feelings between Putin and President Bush, who spoke to each other just last week and are expected to meet at a summit of leaders in Germany next month.

A planned event at which Rice and Putin were to be photographed together and make brief remarks was canceled by the Kremlin, U.S. officials said.