TBILISI, Georgia Unfazed by sharp criticism from President Bush, Russia battled Georgian forces on land and sea, reports said late Sunday, despite a Georgian cease-fire offer and its claim to be withdrawing from South Ossetia, the separatist Georgian province battered by days of intense fighting.
Russia claimed to have sunk a Georgian boat that was trying to attack Russian vessels in the Black Sea, and Georgian officials said Russia sent tanks from South Ossetia into Georgia proper, heading toward a strategic city before being turned back.
The violence appeared to show gargantuan Russia's determination to subdue diminutive, U.S.-backed Georgia, even at the risk of international reproach. Russia fended off a wave of international calls to observe Georgia's cease-fire, saying it must first be assured that Georgian troops have indeed pulled back from South Ossetia.
International envoys were heading in to try to end the conflict before it spreads throughout the Caucasus, a region plagued by ethnic tensions. But it was unclear what inducements or pressure the envoys could bring to bear or to what extent either side was truly sensitive to world opinion.
The United States is waging an all-out campaign to press Russia to halt its retaliation against Georgia for trying to take control of the breakaway province of South Ossetia.
Bush, in an interview with NBC, said, "I've expressed my grave concern about the disproportionate response of Russia and that we strongly condemn the bombing outside of South Ossetia."
On Sunday, Vice President Dick Cheney said that "Russian aggression must not go unanswered and that its continuation would have serious consequences for its relations with the United States."
The sheer scope of Russia's military response has the Bush administration deeply worried. Russia on Sunday expanded its bombing blitz in areas of Georgia not central to the fighting.
Cheney spoke Sunday afternoon with Georgian President Mikhail Saakashvili, Cheney press secretary Lee Ann McBride said. "The vice president expressed the United States' solidarity with the Georgian people and their democratically elected government in the face of this threat to Georgia's sovereignty and territorial integrity," McBride said.
Asked to explain Cheney's phrase "must not go unanswered," White House spokesman Gordon Johndroe said, "It means it must not stand." White House officials refused to indicate what recourse the United States might have if the military onslaught continues.
A Russian official said more than 2,000 people had been killed in South Ossetia since Friday; the figure could not be confirmed independently.
Bush, pressing international mediation, reached out Sunday to French President Nicolas Sarkozy, who heads the European Union. The two agreed on the need for a cease-fire and a respect for Georgia's integrity, White House spokesman Gordon Johndroe said.
The U.N. Security Council met for the fourth time in four days Sunday, with U.S. Ambassador Zalmay Khalilzad accusing Moscow of seeking "regime change" in Georgia and resisting attempts to make peace.
Georgian President Mikhail Saakashvili said one of the Russian raids on the airport area came a half hour before the arrival of the foreign ministers of France and Finland in the country to try to mediate.
Georgian Interior Ministry spokesman Temur Yakobashvili said Russian tanks tried to cross from South Ossetia into the territory of Georgia proper, but were turned back by Georgian forces. He said the tanks apparently were trying to approach Gori, but did not fire on the city of about 50,000 that sits on Georgia's only significant east-west highway.
Russia also sent naval vessels to patrol off Georgia's Black Sea coast, but denied Sunday that the move was aimed at establishing a blockade.
The ITAR-Tass news agency quoted a Russian Defense Ministry spokesman as saying that Georgian missile boats twice tried to attack Russian ships, which fired back and sank one of the Georgian vessels.
South Ossetia broke away from Georgian control in 1992. Russia granted passports to most of its residents, and the region's separatist leaders sought to absorb the region into Russia.
Georgia, whose troops have been trained by American soldiers, began an offensive to regain control over South Ossetia overnight Friday, launching heavy rocket and artillery fire and air strikes that pounded the regional capital Tskhinvali. Georgia says it was responding to attacks by separatists.
In response, Russia launched massive artillery shelling and air attacks on Georgian troops.
Thousands of civilians have fled South Ossetia many seeking shelter in the Russian province of North Ossetia.
"The Georgians burned all of our homes," said one elderly woman, as she sat on a bench under a tree with three other white-haired survivors of the fighting.
She seemed confused by the conflict. "The Georgians say it is their land," she said. "Where is our land, then? We don't know."
The scope of Russia's military response has the Bush administration deeply worried
The U.S. military began flying 2,000 Georgian troops home from Iraq after Georgia recalled them, even while calling for a truce.
"We have made it clear to the Russians that if the disproportionate and dangerous escalation on the Russian side continues, that this will have a significant long-term impact on U.S.-Russian relations," U.S. deputy national security adviser Jim Jeffrey told reporters.
"Georgia expresses its readiness to immediately start negotiations with the Russian Federation on a cease-fire and termination of hostilities," the Georgian Foreign Ministry said in a statement, adding that it had notified Russia's envoy to Tbilisi.
But Russia insisted Georgian troops were continuing their attacks.
Alexander Darchiev, Russia's charge d'affairs in Washington, said Georgian soldiers were "not withdrawing but regrouping, including heavy armor and increased attacks on Tskhinvali."
"Mass mobilization is still under way," he told CNN's "Late Edition."
Georgia's Security Council chief Alexander Lomaia said the Georgian troops had to move out of South Ossetia because of heavy Russian shelling. "Russia further escalated its aggression overnight, using weapons on an unprecedented scale," Lomaia said.
French Foreign Minister Bernard Kouchner called the hostilities in South Ossetia "massacres," hours before he and Finnish counterpart Alexander Stubb left for Tbilisi and a meeting with Saakashvili.
Kouchner said he would deliver a "message of peace" to Georgia and Russia, and call on both countries "to stop the fighting immediately."
Russian Prime Minister Vladimir Putin, meeting Saturday with South Ossetia refugees who had fled across the border to the Russian city of Vladikavkaz, described Georgia's actions as "complete genocide." Putin also said Georgia had lost the right to rule the breakaway province an indication Moscow could be ready to absorb the province.
Russian jets raided several Georgian air bases Saturday and bombed the Black Sea port city of Poti, which has a sizable oil shipment facility. The Russian warplanes also struck near the Baku-Tbilisi-Ceyhan oil pipeline which carries Caspian crude to the West.
Russian officials said they were targeting Georgian communications and lines of supply. But a Russian raid Saturday on Gori near South Ossetia, which apparently targeted a military base on the town's outskirts, also killed many civilians.
Tskhinvali residents who survived the Georgian bombardment overnight Friday by hiding in basements and later fled the city estimated that hundreds of civilians had died.
The Georgian government said Sunday that 6,000 Russian troops have rolled into South Ossetia from the neighboring Russian province of North Ossetia and 4,000 more landed in Abkhazia. The Russian military wouldn't comment on troop movements.
Russia also sent a naval squadron to blockade Georgia's Black Sea coast. Ukraine, where the ships were based, warned Russia in response that it has the right to bar the ships from coming back to port because of their mission.
Both Ukraine and Georgia have sought to free themselves of Russia's influence, and to integrate into the West and join NATO.
Georgia said it has shot down 10 Russian planes, but Russia acknowledged only two.
NATO Secretary General Jaap de Hoop Scheffer said Russia violated Georgia's territorial integrity in South Ossetia and employed a "disproportionate use of force."
Adding to Georgia's woes, Russian-supported separatists in Abkhazia launched air and artillery strikes on Georgian troops to drive them out of a small part of the province they control.
Abkhazia's separatist government called out the army and reservists on Sunday and declared it would push Georgian forces out of the northern part of the Kodori Gorge, the only area of Abkhazia still under Georgian control.
Contributing: David Nowak, Douglas Birch, Jim Heintz, Vladimir Isachenkov, Lynn Berry and John Heilprin