Destabilizing Iran will make another migration crisis in Europe, will divide it politically because of the rise of anti immigrant far right, and finally set up the scene for a big european war for which russia is preparing.
If US hopes to not be involved in it, it will be up for the surprise.
You think migration of refugees will lead to... civil war in Europe? There's a lot of space in Europe – it could accomodate even all 90 million Iranian refugees and not collapse (let us hope Iranian civilians not made into refugees by Trump and Netanyahu).
If US hopes to not be involved in it, it will be up for the surprise.