Now you know why they never ever touch Israel which is just nearby.
I believe IS, just like al-qaeda, went rogue after US dumped them once work is completed.
In the case of IS, they started capturing and beheading white people initially for ransom, but US refuse to pay so they killed them.
IS was used to destabilise Syria, using former Iraqi army Personnel. Hence their attack on Iraq after controlling part of Syria.
Iran then fought alongside US forces to defend Iraq and defeat IS. Trump then assassinated the commander ( Suleymani) that fought alongside US Army who was on a peace mission to end the conflict.
US is the main problem in the middle East. It is creating havoc wherever it goes.