Russian forces on Wednesday built a sentry post just 30 miles from the Georgian capital, appearing to dig in to positions deep inside Georgia despite pledges to pull back to areas mandated by a cease-fire signed by both countries.

Russian President Dmitry Medvedev says his troops will complete their pullback by Friday, but few signs of movement have been seen other than the departure of a small contingent that have held the strategically key city of Gori.

A convoy of flatbed trucks carrying badly needed food aid to one of the areas most heavily hit by the fighting was waved through a checkpoint by Russian soldiers. But conditions throughout much of the country remained tense.

Russian soldiers were setting up camp Wednesday in at least three positions in west-central Georgia. Further east, soldiers were building a sentry post of timber on a hill outside Igoeti, 30 miles from Tbilisi and the closest point to the capital where Russian troops have maintained a significant presence.

A top Russian general, meanwhile, said Russia plans to construct nearly a score of checkpoints to be manned by hundreds of soldiers in the so-called "security zone" around the border with South Ossetia.

And at a military training school in the mountain town of Sachkhere, a Georgian sentry said he feared Russian forces will make good on their threat to return after a confrontation the day before.

The sentry, who gave his name only as Corporal Vasily, said 23 Russian tanks, APCS and heavy guns showed up at the base on Tuesday and demanded to be let in. The Georgians refused and the Russians left after a 30-minute standoff but vowed to return after blowing up facilities in the village of Osiauri, he said.

Georgia's Defense Ministry said Wednesday that Russian soldiers destroyed military logistics facilities in Osiauri, but the claim could not immediately be confirmed.

"We're trying not to provoke them; otherwise they'll stay here for five to six months," Vasily said. He said the school itself had no heavy weapons or other significant strategic value, unlike the military base raided by Russians at Senaki, "where they even took the windows off the buildings."

Russia sent its tanks and troops into Georgia after Georgia launched a heavy artillery barrage Aug. 7 on the separatist, pro-Russian province of South Ossetia. Fighting also has flared in a second Georgian breakaway region, Abkhazia.

The short war has driven tensions between Russia and the West to some of their highest levels since the breakup of the Soviet Union.

A cease-fire signed by the presidents of Russia and Georgia calls for Russian forces to pull back to the positions they held before Aug. 7. The cease-fire allows Russia to maintain troops in a zone extending about 4 miles into Georgia along the South Ossetian border.

The Kremlin said Medvedev told French President Nicolas Sarkozy by phone Tuesday that Russian troops would withdraw from most of Georgia by Friday _ some to Russia, others to South Ossetia and a surrounding "security zone" set in 1999.

The White House made clear it expected Russia to move faster. "It didn't take them really three or four days to get into Georgia, and it really shouldn't take them three or four days to get out," spokesman Gordon Johndroe said.

Col. Gen. Anatoly Nogovitsyn, deputy head of the Russian general staff, told a briefing Wednesday that Russia will build a double line of checkpoints totaling 18 in the zone, with about 270 soldiers manning the front-line posts. He said the security zone would be 25 miles from the strategically key city of Gori, but the city is significantly closer to the zone's presumed boundaries than that.

South Ossetia technically remains a part of Georgia, but Russia has said it will accept whatever South Ossetia's leaders decide about their future status _ which is almost certain to be either a declaration of independence or a request to be incorporated into Russia.

Western leaders have stressed Georgia must retain its current borders.

A U.S. Senate Armed Services Committee delegation is traveling to Georgia to show solidarity with its government and assess the situation after fierce fighting between Georgian and Russian troops.

"This is a moment in history when it is vital for the world's democracies to stand in solidarity," U.S. Sen. Joe Lieberman, I-Conn., said in a statement before the trip.

Lieberman and South Carolina Republican Sen. Lindsey Graham were meeting with Georgian officials as well as with the ranking U.S. general on the ground.

U.S. Brig. Gen. Jon Miller arrived with a team Monday to assess humanitarian needs. About half of the displaced Georgians have taken refuge in schools, municipal offices and even condemned buildings in and around the Georgian capital, Tbilisi.

The Igoeti checkpoint that the aid trucks crossed, about 30 miles west of Tbilisi, is one of the deepest penetrations made by Russian forces into Georgia after fighting broke out in South Ossetia nearly two weeks ago.

The Russian seizure of Gori and villages in the region has left thousands of people with scarce and uncertain food supplies. The nine flatbed trucks carrying aid from the World Food Program could bring them some small comfort for a few days.

On Tuesday, Russian forces drove out of the Black Sea port city of Poti in trucks and armored personnel carriers loaded with about 20 blindfolded and bound Georgian prisoners _ identified by local officials as soldiers and police _ and seized four U.S. Humvees. They reportedly were taken to a Russian-controlled military base nearby, and Georgian Interior Ministry spokesman Shota Utiashvili said Wednesday they still were being held.

Nogovitsyn, the Russian general, indicated his forces may not return the U.S. vehicles, which had been waiting at Poti to be shipped home after being used in recent U.S.-Georgia exercises.

Asked about U.S. demands that Russia return seized weaponry to the Georgian military, he said "we don't intend to give up trophies."

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Associated Press writers Misha Dzhindzhikhashvili in Tbilisi, Georgia; Christopher Torchia in Igoeti, Georgia, and Jim Heintz in Moscow contributed to this report.