Remember that the Iraqis asked for us to come back. The Marines are training the Iraqis who lost 13 in the attack. The daesh were 8 suicide bombers + 16 others, some in Iraqi uniform. God only knows what the Marines’ rules of engagement are.
I guess I think that when the Iraqis asked us to leave, we should have left.
I do not see a national interest there.
The Marines can fire in self defense however they should never have to. The ISFs form the defensive buffer with US and coalition forces providing training, logistics and command oversight. The ISFs around US and coalition bases are of very good quality as Iraqis go. The buffers around these bases are typically measured in kilometers.