Trump is remarkably ignorant of so many things. He hasn't read Sunzi's Art of War (Sunzi Bingfa) either that deals with strategems or strategical principles in case of war and conflict resolution in civil life,

Globally, if Trump is so one-sided to disregard Iran and concentrate on fighting Iranian influence, then he will open up another field of mess that may endanger world peace and global stability in future to come. Most of current Islamist-stimulated terrorism comes from the Sunni site of Islam, and from the Salafist-Wahabite interpretation of (Sunni) Islam followed in Saudi Arabia. Shia terrorism, if at all, is marginal in comparison.

If Iran would recant from its public announcement of destroying Israel, things would look a lot different, and Trump's irrational and absolutely crazy approach would be much more clearly to see for many more people than now.

Such grand plans require Iran to be contained. The first country that trump visited after his inauguration was Saudi Arabia. His attempts to cancel the nuclear deal with Iran and probably start a war with Iran would keep Iran busy and would give more space to Saudi Arabia.