Two recent attacks against the Syrian Arab Army in east-Syria point to a U.S. plan to eliminate all Syrian government presence east of Palmyra. This would enable the U.S. and its allies to create "Sunni entity" in east-Syria and west-Iraq which would be a permanent thorn in side of Syria and its allies.
A 2012 analysis by the Defense Intelligence Agency said:
THERE IS THE POSSIBILITY OF ESTABLISHING A DECLARED OR UNDECLARED SALAFIST PRINCIPALITY IN EASTERN SYRIA (HASAKA AND DER ZOR), AND THIS IS EXACTLY WHAT THE SUPPORTING POWERS TO THE OPPOSITION WANT, IN ORDER TO ISOLATE THE SYRIAN REGIME ...
Note that the described plan mentions exactly two cities - Hasakah and Deir Ezzor.