Russia and Syria unleashed a coordinated assault by land, air and sea on Wednesday, seeking to reverse recent gains by rebel groups that were beginning to encroach on President Bashar al-Assad’s last bastion of power.

Moscow said it had fired 26 cruise missiles on Syrian targets from naval vessels in the Caspian Sea, 900 miles away, though it was not immediately clear whether they hit targets in the area of the ground offensive.

The ground assault, and airstrikes, seemed to focus on an area of northern Hama Province and southern Idlib Province, around three villages that insurgents consider the first line of defense of the strategic Jebel al-Zawiyah area. […]