Russia said on Tuesday that it had dispatched a flotilla of 11 warships to the eastern Mediterranean, some of which would dock in Syria. It would be the largest display of Russian military power in the region since the Syrian conflict began almost 17 months ago. Nearly half the ships were capable of carrying hundreds of marines.

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.