U.S. President George Bush says the Russian military has launched a disproportionate response to Georgia, the former Soviet republic trying to reclaim the disputed territory of South Ossetia.

In an interview with NBC, Bush said that "we strongly condemn the bombing outside of South Ossetia," and shared his concerns with Russian Prime Minister Vladimir Putin and President Dmitri Medvedev.

Meanwhile, U.S. Vice-President Dick Cheney said late Sunday that Russia's military action against Georgia "must not go unanswered," as the conflict over the disputed territory continued to escalate.

Cheney made his remarks while speaking with Georgian President Mikheil Saakashvili. The United States has historically given its support to Georgia, which has been lobbying for inclusion in the North Atlantic Treaty Organization.

According to Cheney's press secretary, Lee Ann McBride, he told Saakashvili: "Russian aggression must not go unanswered, and that its continuation would have serious consequences for its relations with the United States, as well as the broader international community."

The conflict continues to worsen despite efforts by Saakashvili to call for a ceasefire.

Late Sunday afternoon, Russia claimed its forces had sunk a Georgian missile boat in the Black Sea. News agencies reported that the Russians said the Georgian ship was trying to attack its boats.

The fighting began when Georgia sent troops into the breakaway province of South Ossetia on Friday. Georgia had hoped to reassert control over territory, where many residents have Russian passports, but Russian forces intervened.

On Sunday, Moscow expanded a bombing blitz to the Georgian capital and deployed ships off the Georgian coast.

Russia also disputed a claim by Georgia that it has pulled its troops out of South Ossetia and refused to recognize a truce, according to The Associated Press.

A senior Georgian security official had claimed earlier on Sunday that his country's troops had withdrawn from the breakaway province. There were also reports that President Mikhail Saakashvili had ordered a ceasefire.

But Russian Foreign Minister Sergey Lavrov has apparently told his Georgian counterpart that claims of a Georgian troop pullout from the province aren't true. The Russians released a statement about a call between Lavrov and Georgian Foreign Minister Eka Tkeshelashvili.

"The Russian side brought in facts about the presence of Georgian forces in certain neighborhoods of Tskhinvali," said the statement.

Georgia's National Security Council head had earlier claimed that Georgian forces had pulled back from Tskhinvali, South Ossetia's capital.

Government officials in Georgia reportedly declared a ceasefire in South Ossetia on Sunday morning. The country's foreign ministry claimed troops had stopped military activities following orders by Saakashvili.

Georgian officials also said they were ready to negotiate with Russia, which sent troops to the region after Georgia tried to reassert control of the breakaway province late last week.

"Georgia expresses its readiness to immediately start negotiations with the Russian Federation on ceasefire and termination of hostilities," the foreign ministry said in a statement.

Georgia recalls troops from Iraq

But even as Georgia called for a ceasefire, AP quoted a senior American military official who said Georgia has recalled its 2,000 troops from Iraq. The official, who spoke on the condition of anonymity, said the U.S. agreed to transport the Georgian troops home and that "some flights have already begun."

There has been fierce fighting in South Ossetia for the past three days as Georgia's troops pushed to take control of the pro-Russia enclave away from the separatists.

In response, Russia poured troops into the region, repositioned warships and used warplanes to launch air strikes within Georgia itself. On Sunday, Russian warplanes attacked a military jet factory on the outskirts of Tbilisi.

Russia sent its armed forces into South Ossetia on Friday in an attempt to counter a large-scale offensive by Georgia, which had lost control over the province following the breakup of the Soviet Union in the early 1990s.

Separatists in Abkhazia, also backed by Russia, have launched air and artillery strikes against Georgian forces in the upper Kodori Gorge. Fifteen UN military observers were told to leave the area.

South Ossetia has declared independence, but no international government has recognized the declaration. Russia has granted passports to most South Ossetians.

Abkhazia and South Ossetia have run their own affairs since the early 1990s. Both provinces have built ties with Moscow.

With files from The Associated Press