1) Economy – A nuclear Iran would quickly move against its Arab neighbors, dominating the Straits of Hormuz and controlling 40 percent of the world's seaborne petroleum exports. Iran could then wield the ultimate oil weapon – sending petroleum prices skyrocketing and triggering global economic paralysis.
2) Mideast Destabilization – A nuclear Iran would place unparalleled weaponry into the hands of proxy terror regimes including Syria, Hezbollah, Hamas and beyond. A nuclear Iran would trigger mass nuclear proliferation in the Middle East, thus destabilizing an already-volatile region, while undoing decades of international efforts to prevent nuclear proliferation. Further, a nuclear Iran could act on its threat to annihilate the State of Israel, a vital strategic asset and America's closest ally in the Middle East.
3) Jihad – A nuclear Iran would be emboldened to act upon its perceived religious obligation to destroy America the Great Satan, and its incumbent goal of launching an apocalyptic war in order to hasten the messianic Twelfth Iman's pledge of global Islamic domination.