The Islamic State continuing its rapid advance in eastern Syria on Sunday, claiming the capture of another regime military base.

A statement from Islamic State commander Abu Umar al-Shishani (pictured), a Chechen national, said jihadists had completed the takeover of the Regiment 121 base near Hasakeh in eastern Syria, taking artillery, Grad rockets, Konkurs anti-tank missiles, and two tanks.

Weekend reports indicated the Islamic State has also moved into the southern part of Hasakeh city.

Since the breakdown of an effective non-aggression pact two weeks ago, the Islamic State has seized regime positions in northern, eastern, and central Syria, including the Division 17 base near Raqqa. The jihadists captured the al-Sha’er gasfield in Homs Province, although the Assad regime insists it has regained the area in a counter-offensive.

After months of proclamations of victories — benefiting from the Islamic State’s battles with insurgents — the Syrian military now faces pressure on multiple fronts. Over the weekend, it also lost ground to the insurgency in Hama Province, as the Free Syrian Army took army positions and weapons depots near Khattab.

Opposition fighters are also in control of most of the territory between Quneitra and Daraa in southern Syria and recently launched an offensive inside Damascus to drain regime forces and counter the narrative of President Assad’s triumph.