"The United States stands with the democratically elected government of Georgia and insists that the sovereignty and territorial integrity of Georgia be respected," Mr. Bush said sternly during brief remarks in the White House Rose Garden.
"To demonstrate our solidarity with the Georgian people," the president announced that he was sending Secretary of State Condoleezza Rice to Paris to assist the West's diplomatic efforts on the crisis, and then to the Georgian capital of Tbilisi.
He also announced that a massive U.S. humanitarian effort was already in progress, and would involve U.S. aircraft as well as naval forces. A U.S. C-17 military cargo plane loaded with supplies is already on the way, and Bush said that Russia must ensure that "all lines of communication and transport, including seaports, roads and airports," remain open to let deliveries and civilians through.
"To begin to repair the damage to its relations with the United States, Europe and other nations and to begin restoring its place in the world, Russia must keep its word and act to end this crisis," Mr. Bush said.
Mr. Bush was scheduled to leave Washington on Thursday for a two-week stay at his Texas ranch. White House press secretary Dana Perino said Wednesday that he would postpone his trip for "a couple of days."
The president spoke amid a fast-moving chain of events, with Rice canceling a planned news conference and the White House scrubbing its regular morning briefing with reporters. Despite extensive intelligence resources and deep ties to the Georgian military that the U.S. has trained, the administration has struggled to determine whether Russia is pushing deeper into Georgia and threatening Tbilisi.
Neither the president nor his Cabinet has answered questions on the record about the 6-day-old crisis except for remarks that Mr. Bush made in a television interview on the sidelines of the Olympic Games in Beijing.
Mr. Bush spent the morning meeting with his national security team in the White House Situation Room, the nerve center for monitoring international developments. He talked by telephone with Georgia's embattled president, Mikhail Saakashvili and with French President Nicolas Sarkozy, who traveled to both Tbilisi and Moscow and is leading a European Union initiative to bring about peace there.
The administration and its allies are debating ways to punish Russia for its invasion of Georgia, including expelling Moscow from an exclusive club of wealthy nations - the G-7 - and canceling an upcoming joint NATO-Russia military exercise.
"Russia has also stated that it has halted military operations and has agreed to a provisional cease-fire," Mr. Bush said. "Unfortunately we've been receiving reports of Russia actions that are inconsistent with these statements."
Earlier Wednesday, Saakashvili said that Russian troops were completely disregarding a hard-won and much-lauded, continuing a campaign of violence against Georgian citizens that amounted to "ethnic cleansing."
Saakashvili, speaking live via satellite to CBS' The Early Show, said "the situation is dramatic. We are witnessing a new stage of full-blown Russian invasion and aggression against my country."
Speaking earlier in Tbilisi alongside a handful of other presidents from former Soviet states, Saakashvili said he'd had reports that Russian troops were actively seizing more Georgian territory - beyond the borders of two separatist regions.
"In the Georgian region of South Ossetia, Russian tanks are going through villages inhabited by Georgian population and throwing people out of their houses, putting people into concentration camps that they are setting up in those villages, and separating men and women, and doing worst kind of atrocities," the president told The Early Show.
In Georgia's other separatist province, Abkhazia, Saakashvili said Russian troops were "throwing out every single Georgian man, woman and child."
In Gori - 15 miles south of South Ossetia, in undisputed Georgian territory - Saakashvili told The Early Show "regular Russian troops" had "rampaged the town, looted the town."
He said they were stealing household items and "killing people, terrorizing people."
Minutes after the president's interview with CBS News, Russian military convoys were seen heading out of Gori, deeper into Georgia, according to multiple news agencies. Several dozen Russian military trucks and armored vehicles sped south out of Gori, further from South Ossetia and closer to Tbilisi.
The maneuvers were in violation of the French-brokered truce requiring Russia to withdraw its troops to the positions they held before the conflict broke out last week.
CBS News Moscow bureau chief Svetlana Berdnikova said Russia's Defense Ministry flatly denied Wednesday any claims that its forces had moved beyond the borders of the breakaway provinces. The Foreign Ministry refused to comment on the matter.
The head of Georgia's national security council said earlier Wednesday that 50 Russian tanks had entered the strategic Georgian city of Gori.
Lithuanian President Vladas Adamkus, who spoke immediately after Saakashvili at the Wednesday news conference in Tbilisi, railed against Russia's leaders for their allegedly ceaseless military campaign in Georgia.
He backed Saakashvili's call for all Russian troops to be withdrawn from Georgian territory, including Abkhazia and South Ossetia, and berated the Western world for "appeasing" Russia's actions over the past week.
Security council head Alexander Lomaia said that the tanks entered Gori about 9:45 a.m., about eight hours after Georgia accepted the cease-fire previously agreed to by Russia.
CBS News correspondent Richard Roth said the reports have been denied by Moscow. But one resident of the town said, "people are confused, and edgy."
Other witnesses saw the Russians on patrol, and said Russian troops had even robbed some foreign journalists, reported Roth.
Jason Farrell, a reporter with CBS News' partner Sky News, said Wednesday he had seen Russian tanks and supply vehicles inside Gori.
"I'm afraid I've seen it myself," Farrell told Sky via telephone. He said there were numerous reports of people being shot and houses set on fire in the city, and "people are already talking about large casualties."
"I can now see some smoke rising up, so it would suggest there's fighting taking place," he said. He was reporting live from the outskirts of Gori, and he said many small villages in the surrounding area were starting to see fighting.
"One woman came out and collapsed on the floor and said, 'where are our forces? It's the civilians that are on the front line,'" Farrell said. The reporter said he had seen only one Georgian military jeep, about 10 miles away from Gori city center.
Both presidents Saakashvili and Adamkus called Wednesday for "real, international peacekeepers" to be allowed into the region immediately.
European foreign ministers were meeting Wednesday in Brussels to discuss the cease-fire agreement, and France was seeking support from its EU partners for the deployment of European peacekeeping monitors to help defuse the Russia-Georgia confrontation.
But French Foreign Minister Bernard Kouchner said they could only be deployed with the consent of both Russia and Georgia. He avoided the word "peacekeepers," speaking instead of "controllers, monitors, facilitators."
The cease-fire agreement called for both Georgian and Russian forces to retreat to the positions they held before the fighting over the separatist region of South Ossetia began.
Russian officials have denied their forces moving beyond the borders of the two separatist provinces.
Temur Yakobashvili, the Cabinet minister for reintegration, said Wednesday that Georgian troops had been driven by Russian forces from the small part of Abkhazia they had held.
A Russian general on Tuesday said the Georgians had been driven out but by separatist forces and not the Russian military.