US Secretary of State Condoleezza Rice has demanded Russia withdraw all of its troops from Georgia.
After talks with Georgian President Mikheil Saakashvili on Friday, she said: "Russian forces need to leave Georgia at once. This is no longer 1968."
The crisis began when Georgia attacked South Ossetia on 7 August, sparking Russian retaliation. The separatist region is backed by Moscow.
Russian units have routed Georgian forces and continued into Georgia. Top US officials have invoked memories of the Soviet Union's occupation of Eastern Europe during the Cold War.
Georgia is an ally of the United States and aspires to join NATO.
Mr Saakashvili says he's signed a ceasefire with Russia which was brokered by France.
However, he stressed that the ceasefire was not a permanent solution, and said his country would never accept any loss of its territory.
Russian president Dmitri Medvedev says only Russia can guarantee peace in the region.
He also said a deal signed on Thursday between Poland and the United States to base part of a new US missile defence system on Polish soil, was aimed at the Russian federation.