They have got to be confident in Iraq, because from what I’m seeing, they’re moving a lot of the heavy armor they stole back into Syria.
The US, NATO, and Saudi Arabia have been arming and financing Al Qaeda and ISIS for three years to overthrow the secular government of Syria. Despite this the Syrian Army has been kicking their butts.
Uncle Scam couldn't openly give tanks or other heavy weapons to AL Qaeda in Syria no matter how much John McCain wanted to. The backlash in the military and the public would be huge.
So they arranged this bloody and deadly excursion into Iraq, helped by the complete stand down of the Iraqi Army and the non response by the US, NATO and the UN, to get those weapons into the hands of Al Qaeda so they can take out Assad.