President Bush held a press conference Monday denouncing Russia's escalation of violence in the former Soviet republic of Georgia. In a Rose Garden statement, he pressed Moscow to accept an immediate cease-fire and to pull back its troops from the conflict zone.
"Russia has invaded a sovereign neighboring state and threatens a democratic government elected by its people. Such an action is unacceptable in the 21st century," Bush said.
Georgian President Mikhail Saakashvili signed a cease-fire pledge Monday, and at Georgia's request, the U.N. Security Council in New York called an emergency session -- the fifth meeting on the fighting in as many days.
Russian armored vehicles charged into Georgian territory on two fronts today, seizing a military base and four cities, despite diplomatic efforts to halt the fighting and Georgia's president signing a cease-fire agreement.
The Russian offensive had troops poised just inside the rebel province of South Ossetia at the border of central Georgia, but in a surprise maneuver, Russia sent armored units across the border into western Georgia.
A top Russian general told ABC News that the army had no intention of invading Georgian territory.
The invading tanks spilled out of Abkhazia, a second province that has broken away from Georgia, to seize a Georgian military base and a couple of towns near the Black Sea.
Georgian officials and the Echo Moskvy radio station later reported that Russian troops had also surged across the South Ossetian border and taken the town of Gori in central Georgia, a move that could split Georgia in half.
An ABC News team left Gori just hours before the Russians arrived and reported the town was nearly empty except for Georgian soldiers, who were streaming out of town on armored personnel carriers and pickup trucks, yelling that the Russians were coming.
Saakashvili visited the town briefly with the French foreign minister before he was bundled into a car and driven away amid rumors of an imminent attack. The few civilians who remained ran from the streets in panic.
The two-pronged offensive came, despite calls by the European Union to halt the fighting and despite rising tensions between Russia and the United States.
The military showdown has triggered a war of words between Bush and Russian Prime Minister Vladimir Putin.
Bush, who was attending the Beijing Olympics, told NBC Sports that the Soviet offensive was unacceptable.
"I've expressed my grave concern about the disproportionate response of Russia, and that we strongly condemn the bombing outside of South Ossetia," Bush said. "I was very firm with Vladimir Putin." Bush said he made the same point later in a phone call to Russian President Dmitri Medvedev.
Vice President Dick Cheney was more blunt, telling Georgia's president that "Russian aggression must not go unanswered, and that its continuation would have serious consequences for its relations with the United States."
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 attacks continue.
Putin fired back at the U.S. today, indicating he was particularly upset at the American military for flying 2,000 Georgian troops from Iraq, where they were helping out their U.S. allies, back to Georgia.