Russia has placed short range SS-21 missiles in South Ossetia, that could pose a threat to most major Georgian cities," including the capital, Tbilisi, a U.S.Defense official confirmed to FOX News on Monday.

"Anything such as that, or any other military equipment that was moved in would be in violation of this cease-fire and should be removed immediately," Pentagon Spokesman Bryan Whitman said. "The only forces that are permitted to remain under the cease fire agreement are the forces that were in there at the Aug. 6 time frame."

This news came as Russia's deputy chief of staff insists that Russian troops were pulling out of the breakaway region. However, there have been no confirmed signs of a withdrawal.

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• U.N. Reports Over 118,000 Georgians Have Fled Fighting

Russia's deputy chief of staff Col.-Gen. Anatoly Nogovitsyn told a briefing in Moscow that "today, according to the peace plan, the withdrawal of Russian peacekeepers and reinforcements has begun" and said forces were leaving Gori.

However in Gori, Russian forces seemed to be solidifying their positions and the only movement seen by Associated Press reporters was in the opposite direction from Russia — toward the Georgian capital of Tbilisi, 55 miles to the east.

The U.S. State Department was also unable to confirm a Russian troop pullout.

According to the European Union-brokered peace plan signed by both Medvedev and Saakashvili, both sides are to pull back to the positions held before fighting broke out Aug. 7 in South Ossetia.

Nogovitsyn said the Russian troops are pulling back to South Ossetia and a security zone defined by a 1999 agreement of the "joint control commission" that had been nominally in charge of South Ossetia since it split from Georgia in the early 1990s.

Georgian and Russian officials could not immediately clarify the dimensions of the security zone. Nogovitsyn said "troops should not be in the territory of Georgia," but it was unclear if that excluded patrols.

"I think the Russians will pull out, but will damage Georgia strongly," Tbilisi resident Givi Sikharulidze said. "Georgia will survive, but Russia has lost its credibility in the eyes of the world."

Top American officials said Washington would have to rethink its relationship with Moscow.

The United States called an emergency meeting of NATO on Tuesday to discuss the alliance's worsening relationship with Russia, and U.S. Secretary of State Condoleezza Rice flew Monday to Europe to press the American viewpoint.

"I think there needs to be a strong, unified response to Russia to send the message that this kind of behavior, characteristic of the Soviet period, has no place in the 21st century," U.S. Defense Secretary Robert Gates said Sunday.

Rice said Russia can't use "disproportionate force" against its neighbor and still be welcomed into the halls of international institutions.

But neither would be specific about what punitive actions the United States or the international community might take.

For his part, Medvedev defended Russia's actions Monday and issued a stern warning.

"If someone thinks that our citizens can be killed, soldiers and officers who are peacekeepers killed with impunity, we will never permit that," he was quoted by Russian news agencies as telling World War II veterans in the city of Kursk before flying to Vladikavkaz, near South Ossetia, to hand out medals to Russians involved in the Georgia conflict. "Anyone who tries to do so will face a crushing response."

The European Union, meanwhile, said about 70,000 displaced people were around Tbilisi but there was no shortage of food even though Russian forces had blocked 11 trucks carrying in flour.

Daniella Cavini, a spokeswoman for the EU's humanitarian aid office, also said the EU is working with private relief groups to shelter refugees in schools, hospitals, military barracks and a tent camp near the Tbilisi airport.

U.S. Brig. Gen. Jon Miller arrived in Georgia to assess the need for further humanitarian aid. At least six U.S. military flights have arrived in Tbilisi, ferrying everything from cots, sleeping bags and medicine to emergency shelters and syringes.