WASHINGTON (Reuters) - The United States has few options for stopping Russia’s military advance deep into Georgia and is partly to blame for encouraging Georgia’s pro-Western government to overreach, analysts said.

Russian Prime Minister Vladimir Putin arrives in the southern city of Vladikavkaz, located next to the Georgian separatist region of South Ossetia, August 9, 2008. Putin sharply criticized the United States on Monday, saying its support for Georgia in the conflict over the separatist region South Ossetia displayed a cynical Cold War mentality. REUTERS/RIA Novosti/Pool

Despite warnings by President George W. Bush for Russia to “reverse the course it appears to be on” and withdraw its troops to avert a “dramatic and brutal escalation” of violence,” U.S. military intervention in the small former Soviet republic is nearly unthinkable, analysts said on Monday.

There also is little Washington can do diplomatically to restrain the Russians, according to foreign policy experts.

“Let me say at this point that there are no good solutions. Either we have to try to remove them (the Russians) by force or accept a humiliating defeat,” said Dimitri Simes, founding president of the Nixon Center in Washington.

“It is not a happy situation, and we did not have to have this situation, and I think the (Bush) administration has considerable responsibility for that.”

Georgian forces entered separatist South Ossetia last week, trying to retake the pro-Russian enclave that broke away in the 1990s. Moscow, which supports South Ossetia’s independence, responded by sending its troops into Georgia proper.

Georgia has appealed for international intervention and pulled its battered forces back to defend the capital, Tbilisi, as Russian troops pushed deeper into its territory, ignoring Western pleas to halt.

Simes said U.S. encouragement of Georgian President Mikheil Saakashvili, one of Washington’s staunchest allies, may have led him to believe he could get away with military action to take back control of South Ossetia.

The Bush administration has pushed hard for Georgia to join NATO, against European misgivings and Russian fury at the idea.

“Saakashvili was discouraged from attacking Russian troops in South Ossetia but he clearly never was told point blank ‘If you do it, you are on your own,’” said Moscow-born Simes, who was an informal adviser to President Richard Nixon.

‘MISCALCULATION’

Charles Kupchan of the Council on Foreign Relations, agreed that U.S. encouragement may have made Saakashvili “miscalculate” and send Georgian troops into South Ossetia.

“I think in many respects Saakashvili got too close to the United States and the United States got too close to Saakashvili,” Kupchan said. “It made him overreach, it made him feel at the end of the day that the West would come to his assistance if he got into trouble.”

Bush told Russia on Monday to reverse course or risk jeopardizing relations with the United States.

But Washington has limited leverage over Moscow after years of strained relations on a range of issues from Iraq to the United States’ insistence on placing missile defenses in Europe, the analysts said.

The next U.S. president will inherit that chilly relationship. Both presidential candidates -- Republican John McCain and Democrat Barack Obama -- have called for diplomacy to resolve the conflict over Georgia’s breakaway regions.

“When you have very thin relations, it doesn’t give you a lot of diplomatic tools,” said Steven Pifer, a former U.S. ambassador to Ukraine who is now a visiting fellow at the Brookings Institution. “There are not a lot of things in terms of U.S.-Russian cooperation that we can threaten to stop, that the Russians care about.”

Foreign ministers from the world’s leading industrialized states urged Russia to agree to a ceasefire, and the United States sent senior State Department official Matt Bryza to Tbilisi to join international mediation efforts.

A U.S. official said Secretary of State Condoleezza Rice had made more than 90 calls since Friday to find ways to end the conflict and spoke with Russian Foreign Minister Sergei Lavrov on Sunday.

Janusz Bugajski of the Center for Strategic and International Studies said there was still room for a muscular U.S. diplomacy to contain the crisis and support Georgia’s government and territorial sovereignty.

“We need somebody much higher to go to Tbilisi, to demonstrate to Russia that we support this government,” Bugajski said, given the danger of wider conflict in the volatile Caucasus region.