Bahrain is the smallest country in the Gulf and hosts the most consequential piece of American military infrastructure in the Middle East. Naval Support Activity Bahrain, home to the US Fifth Fleet and Combined Maritime Forces, occupies ground in the island kingdom that no other location in the Gulf could replicate — deep-water access, proximity to the strait, political stability sufficient to sustain a permanent large-scale military presence, and a host government whose security dependence on the American relationship is clear-eyed and durable. The base is there because the geography and the politics aligned. Both continue to hold, under conditions that are more complicated than they appear.

The United States Naval Forces Central Command, headquartered at Naval Support Activity Bahrain, is responsible for an area of operations that covers approximately 2.5 million square miles of water. Within that vast theater, no piece of geography concentrates more of its attention, resources, and contingency planning than a transit corridor that is, at its most critical point, narrower than the distance between Manhattan and New Jersey.

The Fifth Fleet’s dilemma is structural. Its mandate is to ensure freedom of navigation through Hormuz and the broader Gulf. The force it faces — the IRGCN — has designed itself specifically to make that mandate as expensive as possible to execute. The disparity in capabilities runs entirely in one direction, and the disparity in objectives runs in the other. The US Navy can destroy every Iranian naval vessel in the Gulf in days. It cannot do that without triggering an escalation sequence that closes the strait for weeks. The IRGCN cannot defeat the Fifth Fleet. It can make the Fifth Fleet’s success cost more than Washington wants to pay.