Moscow ? It may not be a new Cold War, but relations between the United States and Russia are hardly warm these days.

With tensions rising over major policy differences, Secretary of State Condoleezza Rice will meet face-to-face today with increasingly critical Russian leaders, including President Vladimir Putin.

On the plane trip to Moscow, she said “it’s time for intensive diplomacy” on the two nations’ 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 said 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 are 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.

Rice is an expert on the Cold War who first visited Moscow in 1979.