The United States and Europe must "stand up to" Russian aggression and convey to Moscow that it has become increasingly isolated in world affairs, US Secretary of State Condoleezza Rice said Thursday.

In a speech outlining US policy toward Russia following last month's invasion of Georgia and amid rising tension with the West, Rice warned that Russia cannot be allowed to intimidate neighbouring countries and was at risk of losing its standing in international institutions.

"We cannot afford to validate the prejudices that some Russian leaders seem to have: that if you pressure free nations enough - if you bully, and threaten, and lash out - we will cave in, and forget, and eventually concede," Rice was to say at a gathering organized by the German Marshall Fund of the United States, an independent think tank.

"The United States and Europe must stand up to this kind of behavior, and all who champion it," Rice said in excerpts released ahead of the speech by the State Department.

The United States and European allies must demonstrate that Russia cannot benefit from intimidating tactics against former Soviet states and former Warsaw Pact countries in Eastern Europe.

"Not in Georgia - not anywhere," Rice said.

US-Russian relations have worsened in the last few years on numerous fronts, including US plans to base a missile-defence system in Poland and the Czech Republic and western backing for Kosovo's independence earlier this year from traditional Russian ally Serbia. The Kremlin has also felt threatened by NATO's eastward expansion.

The United States has accused Russia of threatening to cut off natural gas supplies to European countries as a political tool to force diplomatic concessions.

Rice also said the United States will not back down from Russia's courting of Western Hemisphere countries like Venezuela, whose socialistic President Hugo Chavez has embraced close ties with Moscow and developed tighter military relations.

Russia has pledged to sell Venezuela large amounts of automatic weapons and fighter planes, and this month flew Cold War-era bombers to the South American country for military exercises, a move that irked Washington.

But tensions peaked on August 7 when Russia launched a massive invasion of Georgia - a US ally - over the disputed breakaway regions of South Ossetia and Abkhazia.

The United States and European Union condemned the assault that was taken after Georgia retaliated against attacks from separatists in South Ossetia. The Russian military drove deep into undisputed Georgian territory and fighting also spread to Abkhazia.

Rice blamed Russia for using the conflict between South Ossetia and Georgia as a basis for a "premeditated" full scale invasion of Georgia designed to oust the country's democratically elected leaders.

"Russia's invasion of Georgia has achieved - and will achieve - no strategic objective," Rice said. "Russia's leaders will not accomplish their primary war aim of removing Georgia's government."

Russian President Dmitry Medvedev and Prime Minister Vladimir Putin have accused the United States of provoking the conflict in Georgia but have provided no evidence to back up the claims. They said military force was ordered to halt Georgian acts of genocide against South Ossetians.