OSLO (AP) -- Secretary of State Condoleezza Rice on Thursday dismissed as "ludicrous" Russian concerns that Washington's plans to deploy anti-missile defenses in Europe would endanger Moscow's nuclear arsenal.

A flurry of high-level talks in recent weeks has failed to soften Russia's public opposition to the U.S. plan to install radar scanners in the Czech Republic and 10 interceptor missiles in Poland. "Let's be real about this and realistic about this. The idea that somehow 10 interceptors and a few radars in Eastern Europe are going to threaten the Soviet strategic deterrent is purely ludicrous and everybody knows it," Rice told reporters before NATO talks with Russia's foreign minister. "The Russians have thousands of warheads."

The missile debate dominated the start of the two-day talks among NATO foreign ministers. But Russian President Vladimir Putin opened another front with a call for a suspension of his nation's participation in a key Soviet-era arms control treaty.

The 1990 Conventional Forces in Europe Treaty regulates the deployment of military aircraft, tanks and other heavy non-nuclear weapons around Europe. The United States and other NATO members have refused to ratify an updated version of the treaty until Moscow abides by its commitment to withdraw troops from the ex-Soviet republics of Moldova and Georgia. "Our partners are behaving incorrectly, to say the least," Putin said in his annual state of the nation address. "They are using the current situation to build up a network of military bases near our borders. What's more, they also plan to deploy elements of anti-missile defense in the Czech Republic and Poland."

He threatened to pull out of the treaty altogether if progress is not made.

Russian Foreign Minister Sergey Lavrov was to join the talks after an opening session among the 26 NATO allies. NATO Secretary General Jaap de Hoop Scheffer told reporters that, "This is a subject which without any doubt will be discussed."

Rice said the U.S. would continue efforts to "demystify" the missile defense plan for the Russians by pushing an offer to cooperate with Moscow by sharing data and technology.

But Russian officials and generals have revived Cold War language in criticizing the American plan, threatening to target the installations in Eastern Europe. The rhetoric has unnerved some in Western Europe, who fear the negative impact on relations with the Kremlin may outweigh any benefits of the missile shield.

"The important thing is to prevent the spiral of mistrust between Russia and the USA," German Foreign Minister Frank-Walter Steinmeier said.

However, NATO diplomats said there was growing support for the U.S. plans among European governments.