MOSCOW — Russian tanks rumbled into the breakaway Georgian republic of South Ossetia on Friday, warplanes launched airstrikes and fighters reportedly made their way over the border, as Moscow pushed closer to full-blown war against U.S.-backed Georgia.
The fighting that erupted between Georgia on the one hand, and Russia and Ossetian rebels on the other, over the mountainous sliver of land threatened to provide a battleground for long-simmering tensions between Moscow and the West.
At nightfall, each side was calling in reinforcements and pumping out radically different versions of the day's events in the region, which is strategically important for its oil and gas pipelines.
A sharp escalation began earlier Friday, when Georgia launched a large-scale, predawn military operation meant to seize control of the rebel region, whose de facto autonomy and ties to Russia have long been an irritant to Georgian leaders. Backed by warplanes, Georgian troops plunged into South Ossetia and waged a hard battle throughout the day for control of the republic's capital, Tskhinvali.
Officials on both sides reported civilian deaths, though estimates could not be confirmed. Hundreds were reported killed in the fighting. South Ossetian officials claimed 1,400 of their people had died.
Each side blamed the other for violating a shaky cease-fire and throwing the republic back into fighting. And both claimed that victory was almost theirs.
Tskhinvali's status remained unclear late Friday. Both sides, by turns, claimed to have seized control of most of the city. Russian troops reported that many of the buildings had been destroyed and that the parliament building burned to the ground. Aid organizations warned that civilians were hiding in basements without water, electricity or medical help.
Georgian officials said warplanes hit Poti on the Black Sea, an oil shipping port. News reports said bombs also fell near the Baku-Tbilisi-Ceyhan oil pipeline.
The United Nations Security Council called its second emergency session in less than 24 hours in an attempt to prevent war, but by Friday evening diplomats remained unable to reach an agreement on a statement calling for negotiations and an end to violence.
In Beijing, where President Bush was attending the Olympics, White House Press Secretary Dana Perino said the United States, which "supports Georgia's territorial integrity," was calling for an immediate cease-fire. The Pentagon has about 200 troops in Georgia training Georgian units deployed to Iraq, officials said.
The Georgian Foreign Ministry, meanwhile, called on the international community to "give Russia the message that invading the territory of a sovereign state and bombing its territory is unacceptable in the 21st century."
South Ossetian leader Eduard Kokoity called the fight a "genocide."
"The latest tragic developments should become the last step toward the recognition of South Ossetia's independence," he told the Interfax news agency. "I am sure that the independence of South Ossetia will be recognized in the near future."
With Russia pitted against U.S.-backed Georgia, the conflict could escalate quickly -- and prove difficult to quell. From Chechnya to Abkhazia, another separatist region of Georgia, Russian-sponsored volunteers were encouraged to join South Ossetia's fight against Georgia, raising the threat of a war that could engulf the historically volatile Caucasus.
On Friday night, a military convoy left the Abkhaz capital and headed for South Ossetia to join the battle, Interfax reported.
The region has emerged as a sort of post-Cold War proving ground where the United States and Russia jockey for influence. Relations between the two countries have chilled under the leadership of former President, now Prime Minister, Vladimir Putin, as an increasingly strong and wealthy Russia seeks to reestablish itself as a superpower.
Georgia is a key player in that contest. A small, mountainous and poor country on Russia's southern flank, it has deeply distressed Moscow by allying itself with the United States. Georgian President Mikheil Saakashvili has sent 2,000 soldiers to fight in Iraq, and he campaigns for North Atlantic Treaty Organization membership.
But Georgia has long been bedeviled by the breakaway republics of South Ossetia and Abkhazia. Both republics fought bloody wars for de facto independence after the Soviet collapse, and have depended on Moscow for everything from passports to political cover. Russian peacekeeping forces have been stationed in the republics for years.
This year, analysts say, Russia seized upon the friendly republics to score a point in its ongoing grudge match against the West. When Kosovo declared independence from Russian ally Serbia, Moscow warned that breakaway regions around the world would be encouraged to follow suit. Critics accuse Russia of fomenting strife in Georgia's rebel provinces to drive the point home.