Russia said on Friday it had completed its pullout of troops from Georgia proper, but the White House swiftly rejected Moscow's claim that it was now in compliance with a French-brokered ceasefire.
Russia said it had left peacekeepers manning checkpoints inside Georgia, stoking Western fears that Moscow aims to keep a stranglehold on the ex-Soviet republic's economy and to annex additional territory to breakaway South Ossetia by stealth.
Earlier, Reuters reporters saw convoys of tanks and trucks heading northwards into rebel-held parts of Georgia .
There was no sign of Russian forces moving on into Russia from South Ossetia, underlining Tbilisi's concern that Moscow plans to maintain a large military presence in that province.
"The pullout was carried out without any incidents and was completed according to plan at 19:50 Moscow time," the Russian Defense Ministry said in a statement.
"Peacekeeping checkpoints in the security zone (inside Georgia ) have started carrying out the tasks set before them. In this way, the Russian side has implemented the agreements set out (by the presidents of Russia and France)," it said.
Washington said the pullout remained unsatisfactory.
"It is my understanding that they have not completely withdrawn from areas considered undisputed territory and they need to do that," White House spokesman Gordon Johndroe told reporters in Texas, where US President George W. Bush was on a two-week working holiday.
Bush earlier on Friday spoke with French President Nicolas Sarkozy about the latest developments in Georgia and the two leaders agreed that "Russia is not in compliance and that Russia needs to come into compliance now," he said.
The top US general in Europe John Craddock, on a visit to Tbilisi, described the Russian pullout, after fighting that has killed hundreds and made refugees of tens of thousands, as "far too little, far too slow".
Georgia also said Russia needed to go further. President Mikheil Saakashvili was due to chair a meeting of the National Security Council late on Friday to discuss latest developments.
A Reuters correspondent saw a convoy of dozens of tanks, armored personnel carriers (APCs) and trucks heading north from central Georgia towards South Ossetia on Friday afternoon.
A Reuters photographer in western Georgia also reported seeing a column including more than 20 tanks crossing into Abkhazia, another Moscow-backed rebel province on the Black Sea.
Russia and Georgia went to war after Tbilisi tried to retake South Ossetia on Aug. 7-8, provoking an overwhelming counter-attack from Moscow.
Georgia's National Security Council secretary Kakha Lomaia said Russian troops had left the key central town of Gori.
But he said Russian forces appeared to have mined a military base. As he spoke, a series of explosions could be heard from its vicinity. A large fire also raged in fields near Gori.
Outside the Black Sea port of Poti, over 120 miles west of the main conflict zone, a Reuters photographer saw Russian soldiers using an excavator to dig a trench at a checkpoint guarded by troops and APCs.
US officials regard a Russian withdrawal from the Poti area, where Georgia 's main east-west highway reaches the coast, as a key test of Moscow's commitment to the peace plan.
Moscow has made clear it intends to maintain a substantial "peacekeeping" force in a large buffer zone bordering South Ossetia and Abkhazia, citing a 1999 accord. Russia says this is needed to prevent more bloodshed and protect South Ossetians - most of whom hold Russian passports - from Georgian attacks.
"The Russians want to have eight peacekeeping checkpoints outside South Ossetia but that is not agreed with us or with international mediators, so it is not Russia's right to decide unilaterally how many checkpoints will be here," Lomaia said.
Georgia says Russia's buffer zone plan violates the ceasefire. It fears Russia could use the vaguely worded ceasefire deal to keep officially-designated peacekeeping forces in control of roads and railways.
The deputy chief of the Russian military's General Staff, Anatoly Nogovitsyn, told reporters those checkpoints retained in a zone along the border between South Ossetia and the Georgian heartland were
A map used by Nogovitsyn at the briefing showed the Russian security zone extending down to the main highway east and west of Gori and included Russian checkpoints on the road itself.
The West is concerned for the stability of energy supplies across a country viewed by many in Moscow as part of Russia's historic sphere of influence.
Georgia is seeking up to $2 billion in aid to repair and develop infrastructure, the head of the US government aid agency USAID told reporters on Friday after visiting Tbilisi.