Islamic State fighters attacked a military airport in Syria’s Homs province on Monday as they pressed a westward offensive against government strongholds, a monitoring group said.

Forays by Islamic State, which is strongest in the northeast and east, into the provinces of Homs, Hama and even Damascus pose a fresh challenge for Syrian President Bashar al-Assad.

Syria’s army has seized control of a swathe of territory from Damascus through the cities of Homs and Hama to the western coast by defeating other, less powerful militias including rebels fighting under the banner of the Free Syrian Army. […]