The Islamic State of Iraq and Syria (ISIS) continues to grow tonight, with the latest reports that they overran the towns of Muhassan, al-Bulil, and Al-Buomar in the Deir Ezzor Province, a cluster of towns along the Euphrates River.

Muhassan is seen as a particularly strategically valuable town, as it is just a stone’s throw away from the city of Mayadin, and the Syrian military’s main eastern airport.

If ISIS manages to take Mayadin, they will effectively control every major city in Deir Ezzor, a major oil-producing province that borders the ISIS-controlled Anbar Province of Iraq.

Some portions of other Deir Ezzor cities, including al-Bukamal, have been contested off and on between ISIS and rival al-Qaeda faction Jabhat al-Nusra, though ISIS seems to be getting the better of most such confrontations, and seem to be moving ever closer to de facto statehood.