"Russian military: You are not a liberating military, you are an occupying force!" one man shouted at the Poti protest. Banners read "Say No to War" and "Russia go home."
On Friday, Russia said it had pulled back forces from Georgia in accordance with a EU-brokered cease-fire agreement.
"There are very specific requirements for Russian withdrawal. Putting up permanent facilities and checkpoints are inconsistent with the agreement. We are in contact with the various parties to obtain clarification," White House spokesman Gordon Johndroe said.
French President Nicolas Sarkozy's office said he had pressed Russian President Dmitry Medvedev during a phone conversation Saturday to quickly remove Russian troops from an axis between the Georgian towns of Poti and Senaki.
Russia's pullback on Friday came two weeks to the day after thousands of Russian soldiers roared into the former Soviet republic following an assault by Georgian forces on the separatist region of South Ossetia. The fighting left hundreds dead and nearly 160,000 people homeless.
It also has deeply strained relations between Moscow and the West. Russia has frozen its military cooperation with NATO, Moscow's Cold War foe, underscoring a growing division in Europe.
On Saturday, residents of the strategic central city of Gori began returning. Chaotic crowds of people and cars were jammed outside the city as Georgian police tried to control the mass return by setting up makeshift checkpoints.
Those who were let through came back to find a city battered by bombs, suffering from food shortages and gripped by anguish.
Surman Kekashvili, 37, stayed in Gori, taking shelter in a basement after his apartment was destroyed by a Russian bomb. Several days ago, he tried to bury three relatives killed by the bomb, placing what body parts he could find in a shallow grave covered by a burnt log, a rock and a piece of scrap metal.
"I took only a foot and some of a torso. I could not get the other bodies out," he said.
His next-door neighbor, Frosia Dzadiashvili, found most of her apartment destroyed, leaving only a room the size of a broom closet to stay in.
"I have nothing. My neighbors feed me if they have food to share," the 70-year-old woman said.
The Russian tanks and troops are now gone from Gori - but other Russian troops are just up the road at a new Russian checkpoint. On Saturday afternoon, several thousand protesters waving Georgian flags approached the Russian position on the outskirts of Gori.
Some soldiers came out of their trenches, but there was no clash. Russian troops also held positions in trenches they had dug near a bridge that provides the only access to Poti. Tanks and armored personnel carriers were parked nearby. Russian troops hoisted both Russian flags and the flag of the Commonwealth of Independent States, or CIS, the union of former Soviet republics that Georgia recently announced it had left.
Emotions ran high as protesters approached a Russian position, but direct confrontation was avoided.
"They have the CIS flag, and that flag is not our Georgian flag," said protester Sulkhan Tolordava. "Georgia is not a member of this organization, so the troops must leave very quickly."
Russia interprets the cease-fire accord as allowing it to keep a substantial military presence in Georgia because of earlier peacekeeping agreements that ended fighting in the separatist areas of Abkhazia and South Ossetia in the 1990s.
But even though Poti is completely outside the buffer zone for Abkhazia, Nogovitsyn said Russian troops are not leaving and will patrol the city.
"Poti is not in the security zone, but that doesn't mean that we will sit behind the fence and watch as they drive around in Hummers," Nogovitsyn said, making an acid reference to four U.S. Humvees the Russians seized in Poti this week. The vehicles were used in previous joint U.S.-Georgian military exercises.
Russian forces also set up a checkpoint near Senaki, the home of a major military base in western Georgia that Georgian troops retook on Saturday. AP video footage of the base Saturday showed it had been heavily looted.
And in South Ossetia, Russian troops erected 18 peacekeeping posts in the "security zone" and planned to build another 18 peacekeeping posts around Abkhazia. A total of 2,600 heavily armed troops the Russians call peacekeepers will be deployed in those regions.
Russia, Georgia and the West are certain to continue the diplomatic struggle over South Ossetia and Abkhazia. The Russian parliament was expected to discuss recognizing the independence of the separatist regions Monday.
In some devastated Georgian towns, the only visitors Saturday were looters, arriving in trucks and cars to take whatever they could find.
In the village of Kekhvi, the ethnic Georgian homes had been burned. An AP reporter saw Ossetian men hauling away cutlery, electronics, blankets, foodstuffs and even Orthodox icons in a looting campaign driven by opportunism and revenge. Some looters even came to pluck ripe peaches off the trees.
"This is not looting, this is trophies," said Garik Meriyev, 32, a stubbled South Ossetian dressed in green camouflage pants, a black baseball cap and dusty jackboots.
He and four other men loaded their yellow Russian-made minibus Saturday with metal pipes, timber and bricks from a burned down house.
"All of this will be destroyed anyway," he said. "But now these things will serve me."
Associated Press writers Misha Dzhindzhikhashvili in Tbilisi, Georgia; Mike Eckel in Gori, Georgia; Yuras Karmanau in Tskhinvali, Georgia; and Jim Heintz and David Nowak in Moscow contributed to this report.