President Trump posted on Truth Social that Iran had 48 hours to reopen the Strait of Hormuz and threatened US attacks on Iranian power plants if it did not.
That threat is strategically significant because the Strait of Hormuz is one of the world’s most important maritime chokepoints. In 2024, oil flow through the strait averaged about 20 million barrels per day, equal to roughly 20% of global petroleum liquids consumption, and about one-fifth of global LNG trade also passed through it.
The legal question, however, is not whether reopening the strait is important. The legal question is whether such strikes would comply with the law of armed conflict (LOAC), the framework governing the conduct of hostilities, which incorporates treaty law, customary international law, and other applicable rules, including those often described as international humanitarian law (IHL).
The United States is bound to comply with LOAC through a combination of treaty obligations it has ratified, such as the Geneva Conventions, and customary international law, even where it has not ratified specific instruments like Additional Protocol I. On that issue, the answer is narrower and less forgiving than political rhetoric suggests.
Distinction and Military Objectives
One basic rule is distinction: parties may direct attacks only against military objectives, not civilian objects. The rule of distinction and the requirement to limit attacks to military objectives are binding as customary international law and are reflected in US doctrine.
A military objective is an object which, by its nature, location, purpose, or use, makes an effective contribution to military action and whose destruction offers a definite military advantage. This is widely accepted as customary international law and reflected in U.S. doctrine; it is also codified in Article 52 of Additional Protocol I.
Customary international humanitarian law states the same core rule: parties must distinguish between civilian objects and military objectives, and attacks may be directed only against military objectives.
That means a power plant is not targetable simply because it belongs to the enemy state or because striking it would create political pressure. A power plant becomes lawfully targetable only if, in the circumstances at the time, it makes an effective contribution to military action and attacking it offers a definite military advantage.
Why Power Plants Raise Dual-Use Problems
Electric grids and generating stations are classic dual-use infrastructure. They often serve both the civilian population and military systems at the same time. The DoD Law of War Manual recognizes that electrical power stations are generally of sufficient importance to a state’s capacity to meet its wartime needs that they may be military objectives in some circumstances.
That point matters, but it does not create a free pass. “Dual-use” does not mean “automatically lawful to destroy.” It means the object requires a fact-specific targeting analysis. If a plant powers air defenses, missile production, command-and-control nodes, naval operations, or other concrete military functions, it may qualify as a military objective.
If the real point is to coerce the government by inflicting broad civilian suffering, the strike would raise serious LOAC proportionality concerns because the law prohibits directing attacks at civilian objects and bars attacks expected to cause incidental civilian harm that is excessive in relation to the concrete and direct military advantage anticipated.
The same body of law also requires feasible precautions in attack, including doing everything feasible to verify that targets are military objectives and taking precautions to minimize incidental civilian harm.
Applying LOAC to Trump’s Threat
So how does that framework apply here? If the idea is “open the strait or we will hit power plants,” the legality would depend on why those plants are being struck and what military function they serve.
If a specific Iranian power facility were supplying electricity to coastal missile batteries, naval mining operations, military radar, or command networks directly involved in blocking Hormuz, a strike might be legally arguable as an attack on a military objective.
If, instead, the threat is to start with “the largest power plant” because knocking out national electricity would force Tehran to change policy, that looks much more problematic. Size and economic importance do not, by themselves, make an object a lawful military objective under LOAC. Nor does the global importance of Hormuz eliminate the duty to distinguish military objectives from civilian infrastructure.
There is also a proportionality problem. Large-scale attacks on electrical infrastructure can foreseeably disrupt hospitals, water pumping, sewage treatment, food refrigeration, and civilian communications. LOAC does not forbid all collateral civilian harm, but it does forbid attacks expected to cause incidental civilian harm that is excessive in relation to the concrete and direct military advantage anticipated.
The Bottom Line
The strongest legal conclusion is this: LOAC does not categorically bar attacks on power plants, because some power infrastructure can qualify as dual-use military objectives. Yet LOAC also does not allow a state to bomb power plants simply to punish, coerce, or create economic pain until a strait reopens. The law requires target-specific proof of military contribution, a concrete military advantage, a proportionality assessment, and feasible precautions.
On the facts publicly available so far, Trump’s statement reads more like a coercive threat against nationally important infrastructure than a publicly articulated, target-specific LOAC justification. That does not make every conceivable strike on Iranian power infrastructure unlawful. It does mean the legality would turn on the particular plant, its actual military role, and the expected civilian consequences, not on the political objective of reopening Hormuz.
