The United States has warned that relations with Russia could be damaged for years if Moscow does not step back from "aggressive" actions in Georgia.
But Defence Secretary Robert Gates said he did not see a need for US military force in Georgia.
His words came as Moscow said the idea of Georgian territorial integrity was an irrelevance.
Russian Foreign Minister Sergei Lavrov said Georgia's breakaway regions - Abkhazia and South Ossetia - would never agree to being part of Georgia again.
Earlier, Russia said it had began handing back the town of Gori to Georgian police but insisted its troops would stay in the area.
More tanks
However, officials in Georgia say at least 100 Russian tanks and other vehicles are moving deeper into Georgian territory.
Georgia attacked the rebel region of South Ossetia from Gori a week ago, prompting Russian retaliation. The Georgians say it followed continuous provocation.
Both sides agreed to a ceasefire brokered by France on Tuesday, amid international concern, but it has seemed fragile so far.
Earlier on Thursday in Moscow, Russia's President Dmitry Medvedev said Russia would respect any decision South Ossetia and Abkhazia made about their future status.
Aid shipments
Meanwhile, the US has sent a second shipment of humanitarian aid into Georgia.
Russia has questioned whether the deliveries contain only humanitarian supplies.
Moscow earlier announced an emergency aid package for South Ossetia. Finance Minister Alexei Kudrin pledged 10 billion roubles ($US414 million) to rebuild the region.
