Even as Russia pledged to begin withdrawing its forces from neighboring Georgia on Monday, American officials said that the Russian military has been moving launchers for short-range ballistic missiles into South Ossetia, a step that appears intended to tighten its hold on the breakaway territory.

The Russian military deployed several SS-21 missile launchers and supply vehicles to South Ossetia on Friday, according to American officials familiar with intelligence reports. From the new launching positions north of Tskhinvali, the South Ossetian capital, the missiles can reach much of Georgia, including Tbilisi, the capital.

The Kremlin announced on Sunday that Russia's president, Dmitri Medvedev, had promised to begin the troop withdrawal in a conversation with President Nicolas Sarkozy of France, who negotiated the six-point cease-fire agreement. Medvedev did not specify the pace or scope of the withdrawal, saying only that troops would withdraw to South Ossetia and a "security zone" on its periphery.

The United States and European leaders reacted with wariness, and Russia's recent military moves appeared to add an element of frustration.

"Well, I just know that the Russian president said several days ago Russian military operations would stop. They didn't," Secretary of State Condoleezza Rice said on NBC's "Meet the Press." "This time I hope he means it. You know the word of the Russian president needs to be upheld by his forces."