A simple explanation of the positions of America and Britain in the Mid East:We support the Iraqi government in the fight against ISIS. We don’t like ISIS, but ISIS is supported by Saudi Arabia whom we do like.
We don’t like Assad in Syria. We support the fight against him, but ISIS is also fighting against him.
We don’t like Iran, but Iran supports the Iraqi government in its fight against ISIS.
So some of our friends support our enemies, some enemies are now our friends, and some of our enemies are fighting against our other enemies, whom we want to lose, but we don’t want our enemies who are fighting our enemies to win.
If the people we want to defeat are defeated, they could be replaced by people we like even less.
And all this was started by invading a country to drive out terrorists who were not actually there until after we went in to drive them out.