A U.S. Navy warship carrying humanitarian aid anchored at the Georgian port of Batumi on Sunday, sending a strong signal of support to an embattled ally as Russian forces built up around two separatist regions.

Ahead of the USS McFaul's arrival, a top Russian general suggested that the presence of U.S. and other NATO ships in the Black Sea would worsen tensions already at a post-Cold War low.

Russia pulled the bulk of its troops and tanks from its small southern neighbor Friday after a brief but intense war, but built up its forces in and around two separatist regions — South Ossetia and Abkhazia — and left other military posts deep inside Georgia.

The guided missile destroyer USS McFaul, loaded with some 80 pallets containing about 55 tons of humanitarian aid, is the first of three American ships scheduled to arrive this week, according to the U.S. Embassy. The aid includes baby food, diapers, bottled water, and milk.

The arrival was a stark reminder that it will take substantial aid and months of rebuilding before Georgia can recover from the war with Russia. Five days of fighting damaged cities and towns across the country and displaced tens of thousands of people.

The commander of the U.S. task force carrying aid to Georgia by ship, Navy Capt. John Moore, downplayed the significance of a destroyer bringing aid. "We really are here on a humanitarian mission," he said.

The McFaul, an Arleigh Burke-class destroyer, is also outfitted with an array of weaponry, including Tomahawk cruise missiles, which can carry either conventional or nuclear warheads, and a sophisticated radar system. For security reasons the Navy does not say if ships are carrying nuclear weapons, but they usually do not.

At dockside in Batumi, with the McFaul anchored offshore, U.S. Navy officials in crisp white uniforms were met Sunday by Georgian officials, including Defense Minister David Kezerashvili.

Speaking to The Associated Press on the aft missile deck of the McFaul, anchored a mile offshore, Kezerashvili said Georgians would feel safer now.

"They will feel safe not because the destroyer is here but because they will feel they are not alone facing the Russian aggression," he said.

The deputy chief of Russia's general staff suggested that the arrival of the ship and those of other NATO members would increase tensions in the Black Sea. Russia shares the sea with NATO members Turkey, Romania and Bulgaria as well as Georgia and Ukraine, whose pro-Western president also is leading a drive for NATO membership.

"I don't think such a buildup will foster the stabilization of the atmosphere in the region," Russia's ITAR-Tass news agency quoted Col. Gen. Anatoly Nogovitsyn as saying Saturday.

The conflict between Russia and Georgia, a small ex-Soviet republic whose pro-Western leaders have tried to shed Moscow's influence and sought NATO membership, has strained Russian-U.S. relations.

Georgia straddles a key westward route for oil from Azerbaijan and other Caspian Sea nations including Kazakhstan, giving it added strategic importance as the U.S. and the European Union seek to decrease Russia's dominance of oil and gas exports from the former Soviet Union.

On Sunday, an oil train caught fire after an explosion in central Georgia, shutting down a main east-west rail line used for oil transport for hours.

The Georgian Foreign Ministry said the most likely cause of the train derailment and fire was a Russian mine planted on the tracks, an opinion echoed by the director of Georgia's railways, Irakli Ezugbaia, and the Interior Ministry spokesman Shota Utiashvili.

Later, Utiashvili said it was possible that debris from explosions at a disused munitions dump nearby hit the train, causing the fire. He earlier had reported that debris from the train blast had caused a fire at the munitions storage site.

Ezugbaia said an investigation was under way and other mines had been found on the tracks. He said the train was carrying crude oil from Kazakhstan transported by an Azerbaijani company to a Georgian Black Sea port.

Hundreds of Georgians flocked back to Gori on Saturday, one day after the Russians withdrew, to begin rebuilding their lives. Their homecoming was laced with despair, disbelief and anger.

"Barbarians, that's what they are. They kill innocent people here ... how many kilometers outside the battlefield? They bombed all over Georgia," Zurab Gvarientashvili, a 31-year-old engineer, said as he viewed his apartment, destroyed by a Russian bomb.

Gori is 20 miles south of the capital of the separatist region South Ossetia, where Georgian forces launched an assault on Aug. 7, sparking the war and an international crisis.

South Ossetian officials accused Georgia on Sunday of building up military forces along the edge of South Ossetia and claimed a Georgian unit fired sporadically at villages overnight. There were no reports of casualties, but South Ossetian spokeswoman Irina Gagloyeva said residents were asking to be evacuated.

Georgian Security Council chief Alexander Lomaia denied that Georgian forces had fired any shots but said Russian forces were obligated to leave positions in the area, which is in Georgia.

Lomaia also said Russian forces were still holding 12 of 22 Georgian servicemen taken prisoner in Poti last week.

Next to one bomb crater in Gori, Merdiko Peredze's goats grazed on burnt grass.

Peredze said he was refugee twice over — once after fleeing his home amid fighting in the early 1990s in Abkhazia and now again, with his house in Gori in tatters.

"I'm an old man but I will return to Abkhazia," he vowed. "Russian, Georgians, Ossetians — we should all be living in peace together, like we did under Stalin."