The most significant issue is Iran's rapid growth and expansion of its sphere of influence, especially in military terms as its Quds Force fighters are now actively engaged in combat operations in Yemen, Syria, Iraq, Lebanon, Afghanistan and Gaza. Iran's military right now is involved in more shooting wars than any other military on the planet (and that includes the US). Why? Because at its core, it is a theocratic state, controlled by a small cadres of mullahs who interpret their particular version of radicalized Islam and view other Muslims as apostates and seek to create their own version of an Islamic Warsaw Pact to offset the perceived threats of Israel and the Sunni Gulf States.