The Caliphate Tries to Survive

This article says that ISIL operations to take Deir Ezzor in Syria where Assad forces have long held out in that city despite jihadi control of the surrounding province is an effort to take a new capital city for their caliphate:

“Deir Ezzor is IS’s next capital when Mosul and Raqqa are taken from it,” said Nicholas A. Heras, a Middle East researcher at the Center for a New American Security, a Washington-based think tank.

I generally don't think much of the leftist Center for No American Security, but when they make sense they make sense.

The article notes that ISIL is using their best troops, the Inghemasyoun (“those who screw submerge themselves”), who are held back to save them for key operations; and that the Syrians lack their usual shock troops supplied by Hezbollah and Iran's Shia foreign legion.

If ISIL takes Deir Ezzor, they will be in a void beyond the area that Syria fights non-ISIL rebels in the west, outside of the region Syrian Kurds will fight ISIL, and outside of Iraq where Iraqi forces fight ISIL now.

So ISIL would remain in Syria with toe-holds in Iraq.

Also, despite Assad's recent victory at Aleppo, if Deir Ezzor falls, will that shake Syrian morale to a dangerous degree? Things looked spooky for Assad after the loss of the outpost at Tabqa.

So far, ISIL efforts in the east aren't distracting the Assad forces from continuing their effort to secure the western part of Syria. The Russian and Iranian-backed offensive in the Aleppo region continues, for example:

Syria's military said Thursday it had captured a string of towns and part of a key highway from the Islamic State group in the northern province of Aleppo.

There have also been operations west of Damascus to secure the capital's water supply.

Will Assad and his Russian, Iranian, and Hezbollah backers attempt to reinforce Deir Ezzor with ground troops and not just support the defenders with air strikes?

Or is Assad satisfied to control his Core Syria and leave the problems in the east to America?

Will America take yet another step to being a de facto Assad ally by supporting the Syrian defenders at Deir Ezzor?

UPDATE: American-backed rebels are seeking to cut off Raqqa from the Deir Ezzor region.  Which adds a sense of urgency for ISIL to conquer Deir Ezzor.