Disguise it as an asteroid and drop it from such a high altitude that the islamofacists in Iran would never believe it was something done by the “Great Satan”. It would have to be judgment from Allah for their indidelity.
Other concepts under study include:
Lockheed Martin’s Kinetic Energy Cavity Penetrator Weapon, which would rely on a phenomenon called “terradynamic cavitation” to drastically reduce drag as the bomb rips through earth and concrete to its target.
The Deep Digger, would sport a 7-barrel rapid-fire cannon in its nosecone that in theory would pulverize earth and concrete in its path as it burrows into the earth. Its developers speculate that a synchronized array of 20 Deep Diggers could produce an artificial earthquake that could collapse tunnels and other underground facilities. The Digger is a joint project from several weapons developers, including designer ARTEC.