the 2017 euphrates crossing offensive was a military offensive launched by the syrian arab army against members of the islamic state of iraq and the levant (isil) in the deir ez-zor governorate, following the breaking of the three-year siege of the city of deir ez-zor. the euphrates crossing offensive, conducted by government troops, was done with the aim of denying us-backed syrian democratic forces and the us itself leverage over the syrian government.