President Bush said Saturday that the two disputed regions at the center of the conflict between Georgia and Russia must remain part of Georgia, but called the signing of a cease-fire between the two nations a "hopeful step."

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Russia's president signed the cease-fire plan Saturday, a day after Georgia's president reluctantly agreed to the pact after lengthy talks with Secretary of State Condoleezza Rice.

Russian forces started to pull back, but later in the day reports were widespread that the military was still digging in, maintaining outposts in Georgian territory.

Bush, speaking at his Crawford, Texas, ranch, issued a stern warning to Russia, whose president said Friday that it's "unlikely" the two breakaway regions — South Ossetia and Abkhazia — will be able to stay in one state with Georgia.

“A major issue is Russia's contention that the region of South Ossetia and Abkhazia may not be a part of Georgia's future," Bush said. "These regions are a part of Georgia — and the international community has repeatedly made clear that they will remain so."

Bush said the United States fully recognizes Georgia's borders and that the country "continues to stand behind" Georgia's democracy and sovereignty. Bush said Russia must abide by the cease-fire that Georgia and Russia have signed.

“Georgia's borders should command the same respect as every other nation’s. There’s no room for debate on this matter," he said.

Russia's foreign minister has said that Georgia could "forget about" getting back those provinces.

Russian President Dmitry Medvedev met in the Kremlin this past week with the leaders of those regions. That was seen as a sign that Moscow could absorb the areas.

Rice did not specify what, if any, repercussions Russia might face for its actions.

"We'll take our time and look at further consequences for what Russia has done," she said. The U.S. and the European Union already have raised concerns "about the way Russia has done this. I think you will start to see reports come out about what Russian forces engaged in."

She said that unlike in the past, Russia cares deeply about its global reputation. "I think actually Russia will care about this talk, because it's not just talk, it's about Russia's standing in the international community," Rice said.

The cease-fire agreement calls for both forces to pull back to positions they held before fighting erupted Aug. 8. That was when Georgia launched a massive barrage to try to take control of the Russian-backed separatist region of South Ossetia. The Russian army quickly overwhelmed the forces of its small U.S.-backed neighbor, and Moscow's troops drove deep into Georgia.

The agreement, Rice said, is specific about future Russian troop presence in Georgia.

"The world has watched with alarm as Russia invaded a sovereign neighboring state and threatened a democratic government elected by its people," Bush said in his weekly radio address. "This act is completely unacceptable to the free nations of the world."

Keeping up the diplomatic pressure, Rice planned to go to Brussels next week for meetings with the foreign ministers of NATO allies and European Union officials.

Senate Foreign Relations Committee Chairman Joe Biden, D-Del., also announced he will visit Georgia over the weekend to meet with the president and Georgians forced to flee their homes.

White House spokesman Gordon Johndroe said Bush spoke with Georgian President Mikhail Saakashvili Saturday afternoon, and "reiterated United States support for the government and people of Georgia."

The crisis has chilled relations between the United States and Russia. The fighting 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 a deal 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.

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 accepting a U.S. missile defense battery, Poland was "exposing itself to a strike."

The missile deal awaits approval by Poland's parliament and signing by Rice during a future visit to Warsaw, possibly in the week ahead.

That is sure to further antagonize Russia. But the U.S. wants to be careful to alienate Moscow and drive Russian leaders away from further integration with the West.

"Russia's actions in Georgia raise serious questions about its role and its intentions in the Europe of the 21st century," Bush said. "In recent years, Russia has sought to integrate into the diplomatic, political, economic, and security structures of the West. The United States has supported those efforts. Now Russia has put its aspirations at risk by taking actions in Georgia that are inconsistent with the principles of those institutions.

"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 act to end this crisis."

The Associated Press contributed to this report.