President Bush warned Russia on Saturday against trying to pry loose two separatist regions in Georgia and said Moscow must end military operations in the West-leaning democracy that once was part of the Soviet empire.

Bush told reporters at his Texas ranch that Russian President Dmitry Medvedev's signing of a cease-fire plan with Georgia was "a hopeful step." But Russia's vision of Georgia without the provinces of South Ossetia and Abkhazia was a nonstarter, the president said.

"These regions are a part of Georgia and the international community has repeatedly made clear that they will remain so," said Bush, Secretary of State Condoleezza Rice at his side. "There's no room for debate on this matter."

The long-simmering dispute over those breakaway areas turned to war this month after Georgia launched a massive barrage to try to take control of South Ossetia. The Russian army quickly overwhelmed the Georgian forces and drove deep into its neighbor.

Russia's attack has caused serious strains in relations with the West and heightened fears in the young democracies of Eastern Europe.

Bush discussed the situation for nearly an hour with Rice, who arrived at the ranch around 5:30 a.m. local time from a quick trip to Georgia. They were joined via secured videoconference from Washington by other members of Bush's national security team, including Vice President Dick Cheney, Defense Secretary Robert Gates and national security adviser Stephen Hadley. Bush also spoke to Georgian President Mikhail Saakshvili, reiterating U.S. support.

The Russian foreign minister, Sergey Lavrov, said this past week that Georgia could "forget about" getting back South Ossetia and Abkhazia, which sympathize with Moscow. Medvedev recently met at the Kremlin with leaders from those regions, raising the prospect Russia could absorb them.

Bush countered that Georgia's borders need to be respected. He said the U.N. Security Council had passed numerous resolutions based on the premise that South Ossetia and Abkhazia remain within Georgia and that international negotiations seek to resolve conflicts in those areas. "Russia itself has endorsed these resolutions," Bush said.

The chilling of relations between Washington and Moscow comes as the U.S. is sealing the deal on a missile shield in Europe _ an issue already unraveling ties between the two former Cold War foes. Poland and the U.S. signed an agreement Thursday for Poland to accept a missile interceptor base as part of a system the U.S. says is aimed at blocking attacks by adversaries such as Iran. The missile deal awaits approval by Poland's parliament and signing by Rice during a future visit to Warsaw, possibly in the week ahead.

Moscow feels it is aimed at Russia's missile force. A Russian general was quoted by Interfax News Agency on Friday as saying that by deploying the system, Poland is "exposing itself to a strike _ 100 percent."

Keeping up the pressure on Russia, Rice plans to go to Belgium this coming week for meetings with the foreign ministers of NATO allies and European Union officials to underscore support for Georgia. Bush, who discussed Georgia in calls Saturday to Canadian Prime Minister Stephen Harper and Latvia President Valdis Zatlers, is expected to continue his telephone diplomacy while on vacation.

At the request of Saakshvili, Senate Foreign Relations Committee Chairman Joe Biden, D-Del., scheduled a trip to Georgia this weekend for meetings with government officials as well as citizens forced to flee their homes.

Rice says the time had come to talk about the consequences Russia should suffer as a result of its actions in Georgia, yet she declined to possible repercussions it could face.

At the end, perhaps the only thing Russia will have proved is that "they can use their overwhelming regional military power to beat up on a small neighbor," she said.

"I don't think that's actually a very good place from which to proceed on an argument that Russia ought to be considered a responsible member of the international system."

When the Soviet Union invaded Czechoslovakia in the 1960s, it occupied the capital, overthrew the government and paid no consequence because it did not care about its international standing, Rice said. "That's not Russia of 2008," she said, adding that Medvedev recently outlined a forward-looking strategy for Russia and its further integration into the international economy. "That's at stake."

The cease-fire deal, which Saakshvili signed Friday after lengthy talks with Rice, calls for both Russian and Georgian forces to pull back to positions they held before fighting erupted Aug. 8.

Russian forces withdrew Saturday from the center of a town not far from Tbilisi, the capital. But Lavrov suggested there would be no immediate broader withdrawal. Lavrov said Russia would strengthen its peacekeeping contingent in South Ossetia, and that afterward, Russian forces sent in to handle the conflict would be withdrawn.

Asked how much time that would take, he responded: "As much as is needed."

Rice bristled at this, saying that the text of the cease-fire agreement, negotiated by French President Nicolas Sarkozy, the current leader of the European Union, outlined a very limited mandate only for Russian peacekeepers who were in Georgia at the time hostilities escalated. She said the agreement specifies that these initial peacekeepers can have limited patrols in a prescribed area within the conflict zone and would not be allowed to go into Georgian urban areas or tie up a cross-country highway.

According to Rice, Medvedev told Sarkozy that the minute the Georgian president signed the cease-fire agreement, Russian forces would begin to withdraw.

"So, from my point of view _ and I am in contact with the French _ the Russians are perhaps already not honoring their word," Rice said.

But she added that now that the Russian president had signed it too, she expects Russian forces to withdraw expeditiously.

___

Associated Press writers Mansur Mirovalev and Christopher Torchia in Georgia and Jim Heintz in Moscow contributed to this report.