MOSCOW — Russia sent warships to the eastern Mediterranean Sea on Tuesday, the Defense Ministry announced, in what appeared to be preparation for a possible evacuation of Russian citizens from Syria.

Russian officials began formulating plans during the summer for an evacuation, but have delayed announcements, analysts say, to avoid signaling a loss of confidence in President Bashar al-Assad, a longtime strategic ally. Moscow staunchly opposes international intervention in Syria and has blocked United Nations Security Council resolutions meant to force Mr. Assad from power. Officials have repeatedly said that Russia’s position has not changed.

However, Moscow has signaled in recent days that it sees Mr. Assad’s forces losing ground, and that it is beginning to prepare for a chaotic transition period. One immediate concern is the large number of Russian citizens scattered across Syria, as a result of decades of intermarriage and longstanding economic ties.

Late on Monday, Russian diplomats said that two Russian citizens had been kidnapped by an armed group. The two Russians, evidently workers in a privately owned steel factory, were seized as they traveled on a road between Homs and Tartus and were held for ransom. An Italian citizen, Mario Belluomo, was abducted with them, the Italian Foreign Ministry said.