The announcement appeared intended to punctuate Russia’s effort to position itself as an increasingly decisive broker in resolving the antigovernment uprising in Syria, Russia’s last ally in the Middle East and home to Tartus, its only foreign military base outside the former Soviet Union. The announcement also came a day after Russia said it was halting new shipments of weapons to the Syrian military until the conflict settled down…

But the unusually large size of the force announced on Tuesday was considered a message, not just to the region but also to the United States and other nations supporting the rebels now trying to depose Syria’s president, Bashar al-Assad…

The Russian announcement got a muted response in Washington. “Russia maintains a naval supply and maintenance base in the Syrian port of Tartus,” said Tommy Vietor, a spokesman for the National Security Council. “We currently have no reason to believe this move is anything out of the ordinary, but we refer you to the Russian government for more details.”