GORI, Georgia — President Medvedev of Russia said yesterday that Georgian actions would not go “unpunished,” as America accused Moscow of deploying short-range missiles within range of Tbilisi, the Georgian capital.

Amid few signs that the Kremlin was honoring its latest pledge to withdraw troops, Mr. Medvedev threatened to “crush” any other ex-Soviet states that attempted to follow Georgia’s example by killing Russian citizens.

For the first time since the conflict began 11 days ago, Mr. Medvedev was allowed to stand in for Prime Minister Putin, the, who has clearly been in charge of running Russia’s war.

Giving a passable imitation of his predecessor, the president — who has been given coaching to imitate Mr. Putin’s abrasive style — adopted an uncompromising position that appeared designed to defy America, which has backed Georgia during the conflict.

“What the Georgian authorities did exceeded human understanding,” he told troops at a base in Vladikavkaz, a city in the Caucasus close to the Georgian border. “Their actions cannot be explained and moreover must not go unpunished.” Mr. Medvedev gave no hint as to what further retribution against Georgia he sought. Russia has already announced plans to launch a genocide investigation against the Georgian government, perhaps with the view to bringing war crimes charges against Georgia’s President Saakashvili.

Meanwhile, Pentagon officials accused Russia of deploying short-range SS-21 missiles inside the Georgian breakaway region of South Ossetia, a move that is likely to unnerve Mr. Saakashvili’s government and undermine the already fragile ceasefire.

The SS-21 was used with devastating consequences against separatist rebels in Chechnya. Russia claimed it had begun to pull its troops out of undisputed Georgian territory, but if it was doing so the withdrawal seemed more cosmetic than substantial.

An American defense official said that Russia was actually sending more troops to South Ossetia and another pro-Russian enclave in Abkhazia.

“We’re seeing them solidify their positions,” the official was quoted as saying.

At a road junction 25 miles from Tbilisi, a confrontation brewed between Georgian policemen and Russian soldiers intent on entrenching themselves in new positions close to the capital.

A Russian commander broke the impasse by ordering the column of personnel carriers to plough their way through two police cars blocking the track.

Asked where they were going, a Russian soldier on top of one of the carriers replied: “Tbilisi. Get your car out of the way before we crush it too.”

There was little sign of withdrawal from other major towns like Kaspi, Zugdidi, and Senaki that have fallen under effective Russian occupation. Six Russian checkpoints blocked the route to the strategic town of Gori, which Russian officers prevented journalists from entering.

Mr. Medvedev sent an undisguised message to other ex-Soviet countries thinking of challenging Russia’s authority.

“If anyone thinks that they can kill our citizens and escape unpunished, we will never allow this,” he said. “If anyone tries this again, we will come out with a crushing response. We have all the necessary resources, political, economic and military.”