South Korea is among the most energy-import-dependent economies of any significant size in the world. It has no domestic oil production, minimal natural gas reserves, and a geography that makes pipeline connections to alternative supply sources impossible. Its entire hydrocarbon supply arrives by sea, a majority of it from the Persian Gulf, and all of the Gulf portion transits the Strait of Hormuz. The country has built one of the world’s largest economies and most sophisticated industrial sectors on an energy supply foundation that is concentrated in a single maritime corridor controlled in part by a government that has expressed willingness to disrupt it.

Global oil markets operate with a margin of production capacity that is not currently being used. This spare capacity — oil wells that are drilled and capable of producing but are held back to manage price levels within OPEC+ target ranges — is the primary buffer that the market can deploy in response to supply disruptions. The overwhelming majority of it sits in the Gulf. In the event of a Hormuz closure, that spare capacity would be simultaneously the most valuable resource in global energy markets and the one most completely inaccessible, because the wells that hold it are connected to export terminals that require the strait to reach their buyers.

Iran has invested more systematically in anti-ship missile capability than any other aspect of its naval force development over the past three decades. The investment reflects the operational logic of the IRGCN’s Hormuz doctrine: surface ships and tankers transiting the strait in a contested environment must be threatenable from multiple vectors simultaneously, and missiles — launched from shore, from surface vessels, from aircraft, and eventually from submarines — provide the most cost-effective way to achieve that coverage. The resulting arsenal is among the largest and most diverse anti-ship missile inventories of any regional power.

Every serious analysis of Hormuz closure scenarios eventually arrives at the same question: how much oil can get out without using the strait? The answer, consistently, is not enough — and understanding why requires examining the bypass infrastructure that exists, the infrastructure that has been proposed, and the fundamental mismatch between pipeline capacity and the volumes the strait normally moves.

The numbers establish the problem. On a normal day, somewhere between 17 and 21 million barrels of crude oil and petroleum products transit Hormuz. The combined nameplate capacity of all existing bypass pipelines is a fraction of that figure, and nameplate capacity is not operational capacity. The infrastructure must be maintained, staffed, protected, and in some cases reversed from its normal flow direction before it becomes useful in a closure scenario. The gap between what the strait moves and what the alternatives can handle does not close quickly.

The Strait of Hormuz has never been closed. The threat of closure has been used repeatedly as a diplomatic instrument by Iran, and incidents in the strait have periodically elevated insurance premiums, rerouted tankers, and spiked oil prices. What has not happened, in the modern era of global oil dependence, is a complete cessation of transit. This absence of precedent does not mean the scenario is implausible. It means that the consequences of closure must be modeled rather than observed, and the models are sobering.

Operation Earnest Will, the 1987-1988 American escort operation for reflagged Kuwaiti tankers, cost the United States approximately five billion dollars in 1987 currency — a figure that, adjusted for inflation and accounting for the expansion of the threat environment since then, understates what a comparable operation would cost today. The escort problem in the modern strait is harder, not easier, than it was during the Tanker Wars. More threats, more capable threats, more vessels requiring protection, and a global economy that is more exposed to disruption than it was forty years ago. The numbers for a sustained escort operation in the contemporary Gulf are large enough that the economics of protection become a strategic variable independent of the purely military calculations.

The March 2023 agreement restoring Saudi-Iranian diplomatic relations, brokered in Beijing over four days of talks that surprised most Western analysts by the speed and apparent completeness of their outcome, was described at the time as a potential transformation of Gulf security dynamics. The more accurate framing is that it was a managed reduction in operational hostility between two states whose fundamental interests remain incompatible and whose competition for regional influence has been paused, not resolved. The strait has been somewhat quieter since the agreement. The conditions that make it dangerous have not changed.

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.

The Islamic Revolutionary Guard Corps Navy does not train to defeat the United States Navy in open water. It trains to make the cost of operating in the strait prohibitive. These are different strategic problems with different solutions, and the IRGCN has spent four decades refining the second one while ignoring the first.

The doctrine that has emerged from this period is sometimes called asymmetric maritime warfare, which is accurate as far as it goes. What the label understates is the geographic specificity of the strategy. The IRGCN is not a general-purpose force. It is a Hormuz force. Every element of its order of battle — the fast attack craft, the anti-ship missile batteries, the submarine fleet, the mine warfare capability, the shore-based artillery — is oriented around the same twenty-one-mile problem.

The strategic partnership between Russia and Iran has been deepening since 2022 in ways that have direct implications for the Persian Gulf security environment. The relationship is not an alliance in the formal sense — no mutual defense treaty binds Moscow and Tehran, and the two countries have a long history of friction and competing interests that did not disappear when their shared confrontation with the West provided new incentives for cooperation. What has emerged is something more specific: a bilateral relationship structured around shared sanctions exposure, complementary military needs, and converging interests in reducing American influence in the regions that matter to each of them.