U.S. Power, Not International Law, Determines Whether the Strait of Hormuz Is Open

By Andrew C. McCarthy

Tuesday, June 30, 2026

 

Combat in the Persian Gulf is once again tenuously paused, but it escalated over the weekend, after last Thursday when Iran’s Islamic Revolutionary Guard Corps forces conducted a drone strike against the Ever Lovely, a container vessel that was attempting to pass through the Hormuz Strait.

 

The weekend’s fighting is a timely reminder. The strait (a narrow international shipping channel that 20 percent of global sea trade, including vital energy commerce, passes through) has been kept open since Ayatollah Ruhollah Khomeini’s 1979 revolution by one thing and one thing alone: American power. There are no international law restraints to which the Iranian regime is or will agree to be bound.

 

The latest episode, like all the rest since early April, reaffirms that it takes two to make a cease-fire. President Trump’s illusions of grandeur notwithstanding, he is powerless to dictate one unilaterally.

 

Meanwhile, everything the president has done since he launched the war in late February — the unilateral military aggression, the unhinged Trumpian twaddle on social media, the inevitable climbdowns, the self-contradictory claims about the state of the conflict and the nature of the Iranian regime — has convinced the IRGC and other Iranian leaders that their control of the strait is analogous to their relentless pursuit of nuclear weapons. That is, it’s worth fighting for at all costs since it could shift the strategic balance in the regime’s favor, despite domestic and foreign hopes for the regime’s demise.

 

On Friday, I addressed one of the two principal follies of the Trump administration’s approach to the war: the mulish failure to grasp the regime’s apocalyptic interpretation of Islam. Tehran’s hegemonic ambitions and endemic anti-Americanism make negotiating with it pointless. Regime operatives are indoctrinated in the jihadist conception of war as deception (as Islam’s prophet instructed). Therefore, nothing regime operatives say in negotiations is trustworthy, and nothing to which they “agree” in a writing — such as Trump’s memorandum of understanding — is worth the paper it’s written on.

 

Since survival is the highest priority, it is especially crucial to grasp the regime’s deception doctrine when it believes it is in an existential crisis. The fact that Trump was bluffing about “regime change” and killing “a whole civilization” does not change the Iranian regime’s ideology.

 

Now let’s turn to the other administration folly: the notion that there is some tenet or norm of international law regarding free transit through the strait that Iran has previously accepted and will eventually come around to again.

 

It’s just not true.

 

What has kept the strait open since President Reagan attacked Iran’s forces and sank most of its navy in the 1988 tanker war has been the jihadist regime’s belief that the United States government regards free shipping through the channel as a vital interest. So much so that, if the regime challenged the status quo, our armed forces would surely be deployed to fight to a decisive conclusion that could be ruinous for Tehran.

 

Free shipping through the strait, and the expectation that it would persist because of American power, was the state of play on February 28. That’s when the president, without a specific congressional authorization or American public support, unilaterally ordered the aerial invasion of Iran in a palpable attempt to force a quick surrender. Trump’s gut told him a Venezuela-style taming of the historically implacable jihadist regime was in the cards. He listened to what he wanted to believe, even though U.S. military and intelligence analysts warned him that a quick surrender was unlikely and that Iran could respond by closing the strait and attacking regional U.S. allies, especially those that host American military installations.

 

Iran responded just as our analysts predicted it would. The strait was de facto closed: Iran essentially warned that ships attempting to transit through could expect to be attacked; it struck a handful of vessels and planted some mines. This persuaded insurers not to indemnify shipping through the strait and the crews themselves not to attempt passage.

 

The administration’s initial response was to deny that the strait was closed (on the risible theory that ships could attempt to pass through . . . if they were willing to run the suicidal risk). That soon gave way to a claim that, by obstructing commerce on “international waters,” Iran was in violation of international law and needed to stand down or face global condemnation (because, y’know, the world’s leading state sponsor of jihadist terrorism famously frets about what people are saying in Washington and European chancelleries).

 

Alas, the American international-law rhetoric is untenable.

 

The overarching assumption of civilized nations is that a country’s territorial waters extend for twelve miles from its coastline. Beyond that lies the open seas, where transit is essentially free. The Hormuz Strait, however, is only 19 miles wide at its narrowest point. Hence, under the default formula, the strait is not part of international waters; at any point in the narrows, it is within the territorial waters of either Iran or Oman, the relevant coastal states.

 

I use the term “the default formula” advisedly. The twelve-mile rule comes from a multilateral compact, the United Nations Convention on the Law of the Seas (UNCLOS), which was completed and opened for signing in 1982, during the Reagan administration and three years after Khomeini’s revolution in Iran. UNCLOS has special rules (in its articles 34–41) that apply to “straits used for international navigation,” such as the Hormuz Strait. These rules generally mandate free transit. This means that the strait is not part of international waters; rather, free transit is granted under UNCLOS rules in light of the strait’s significance to global trade.

 

Here’s the problem: Neither the United States nor Iran ever ratified UNCLOS.

 

The American objection to the treaty has nothing to do with the rules applicable to narrow sea channels. Those rules promote America’s interests. Although the U.S. was deeply involved in crafting UNCLOS, our government never ratified it for two reasons. First, as the world’s dominant naval power and guarantor of free global trade, it would be foolish to forfeit sovereign freedom of action to an international institution that, like the U.N. itself, would have anti-American tendencies. Second and relatedly, UNCLOS provisions related to seabed mining are objectionable.

 

The Iranian complaint is more specific to the Hormuz Strait. While the Khomeini regime purported to sign the treaty (during the brutal Iran-Iraq war), it has never ratified UNCLOS precisely because it realized that its geographical influence over the strait is a major strategic advantage.

 

Although it has not ratified UNCLOS rules related to narrow trade routes, the U.S. approves of them. Consequently, it argues that these rules are so universally accepted that they have evolved into supposedly binding customary international law. Iran, by contrast, observes that a nation may not be bound by international compacts that it has not ratified under its domestic law — the venerable principle of pacta tertiis nec nocent nec prosunt (agreements neither harm nor benefit third parties). Iran shrewdly calculates, moreover, that the United States would never agree, based on anything as vague as customary international law, to be bound against its interests by treaty terms, largely crafted by its enemies, to which it never lawfully assented.

 

This spotlights the weakness of the current American position. There are sea lanes on both the Iranian and Omani sides of the strait. To break the Iranian impediment, the Trump administration has encouraged ships, such as the Ever Lovely, to cross on the Omani side — i.e., beyond twelve miles from Iran’s coastline. This, our diplomats contend, is outside of Iran’s territorial waters, even though it is not, strictly speaking, “international waters” (being within Oman’s jurisdiction).

 

But such contentions assume Iran’s indulgence of UNCLOS. The regime, to the contrary, does not agree that it is bound by either UNCLOS’s twelve-mile territorial waters rule or its free-transit provisions for narrow straits. And even if a non-UNCLOS nation were to accept those terms, the Iranian regime would argue that they are inapplicable in wartime. In that connection, the regime maintains that it was Trump who started the war, and that its responsive closure of the strait is consistent with its sovereign international-law right of self-defense.

 

What’s more, the regime scoffs at the notion that the United States is free to eschew ratification of UNCLOS yet simultaneously claim that UNCLOS provisions it likes are somehow binding on another non-ratifier.

 

Our government and our allies can quibble about some or all of this. Western diplomats counter that Iran benefits from international trade and has waived its objections through decades of abiding free transit through the strait. Maybe so, but such pleading misses the point.

 

The international realm is not like our domestic rule of law. In our own country, we are one people united by our national Constitution, which binds us to accept properly enacted laws, including those of states in which we don’t reside. In international relations, by contrast, even ostensibly binding commitments are often ignored, rescinded, or flat-out broken. What undergirds international agreements are not courts or legal arrangements; it is the perception that severe sanctions, up to and including the use of force, could be the wage of undermining them.

 

All the more, that is the case when there are no binding commitments.

 

The Hormuz Strait has been opened because the Khomeini-founded government was convinced, especially after the tanker war, that the American military response to an Iranian attempt to close the strait would be devastating. In the years that followed, as long as the Iranian regime did not believe it faced an existential threat from the United States, it tried neither to close nor to toll the strait, calculating that the potential cost of a certain American military response was not worth paying.

 

But times have changed. Once President Trump threatened regime change, the regime had nothing left to lose. So it played its ace in the hole. If a U.S. president is going to threaten regime change — while intensively bombing regime targets and thereby demonstrating to the regime that he might be serious — then that president had better be ready to finish the job because the regime is going to resort to measures reserved only for such existential peril.

 

When it resorts to such measures, America’s stark alternative is to escalate and force the regime’s surrender on our terms or capitulate and accept a new reality that would have been understood as intolerable just four months ago. That is why I continue to believe the president should seek congressional authorization to use force to open the strait. Regardless of how we got to this point, and all righteous objections to the administration’s heedless approach, our enemies’ claim to control this critical channel threatens our vital security and economic interests. That should be unacceptable to Congress. A congressional authorization would convey seriousness of purpose to Tehran — something sorely needed at the moment.

 

The Hormuz Strait has been opened for the past four decades, not because of any consensus about international waters and commerce rules applicable to narrow sea lanes. It has been open — and Americans and the world have flourished from global trade — because the jihadist regime in Tehran understood that the United States would not tolerate Iranian restrictions. No parchment promises will change that. President Trump raised the stakes. Now the American choice is to force the regime to stand down or suffer a humiliating defeat that empowers our enemies.