No Strait answer: Can international law stay afloat in Hormuz?

On Sunday, President Donald Trump stepped in to raise the stakes of an already volatile standoff, announcing that the United States Navy would begin “BLOCKADING” the Strait of Hormuz — delivered, in classic Trump fashion, the emphatic all-caps. The deadline passed at 7pm (PST) on Monday.

The developments came after a night of diplomacy in Islamabad that promised more than it delivered, with inconclusive takeaways and very little to show for 21 hours of deliberations. The negotiations ended with a terse briefing from JD Vance, confirming what everyone had been hoping to avoid: nothing had been agreed.

Judging from the string of off-the-cuff, rhetorically charged posts on Trump’s Truth Social feed, he appears to have revived what once again looks like the ‘madman theory’ — using brinkmanship and unpredictability as a strategic bargaining chip. He seems to be signalling that if Iran can rattle markets by blocking one of the world’s primary energy arteries, Washington can rattle them harder.

The rationale is pretty straightforward: either every ship sails freely, or none do.

But can he realistically do that? Can any state, however powerful, seal off a chokepoint governed by transit passage rights designed to prevent precisely this kind of unilateral control?

Set aside the legal abstractions and a layperson is still left wondering: if Iran has effectively shut the Strait of Hormuz, what exactly is America threatening to block? How does one close a door that’s already been shut?

As the world tries to make sense of a threat that seems to defy logic and law in the same breath, this piece turns to voices steeped in international maritime and security law to cut through the noise and explain its implications.

In a politically charged climate today where treaties are signed, unsigned, and at times strategically ignored, Dr Sikander Ahmed Shah, Professor of Law at LUMS, argued that the 1982 United Nations Convention on the Law of the Sea (UNCLOS) continues to bind states regardless of formal consent.

He addressed a common misconception about treaty participation. While both Iran and the US have not signed the UNCLOS, he noted that they may nonetheless be bound by its core provisions, which have crystallised into customary international law.

In this sense, customary international law is formed through consistent state practice and a sense of legal obligation.

A notable illustration of this is how far a country’s territorial sea extends. Today fixed at 12 nautical miles, this boundary was not always so.

Historically, many states followed the “three-nautical-mile rule.” This limit was based on a practical military consideration: coastal artillery in earlier centuries could only fire cannonballs about three nautical miles out to sea. So, states treated only that distance as the area they could realistically defend and control. As a result, ships from other countries would stay beyond this range to avoid provoking coastal defences. Over time, this repeated practice, accepted by others, solidified into customary law.

Before any discussion of blockades or chokepoints, Shah insisted on understanding the basics: the layered structure of maritime zones.

“States exercise full sovereignty over the first 12 nautical miles of sea adjacent to their coast which is termed as the territorial sea,” he explained, adding that beyond that stretches the 200-nautical-mile exclusive economic zone (EEZ), and further still, in some cases, the continental shelf that can extend up to 350 nautical miles. Each layer, as he described it, is a negotiated gradient of sovereignty and must be treated as that.

The Strait of Hormuz problem

Shah, also a former legal adviser to Pakistan’s foreign ministry, addressed the question of navigation rights that govern who can move through the territorial sea and under what conditions.

He said that every ship, vessel, submarine or even a military ship, has a right of innocent passage in the territorial sea. But this right is not unlimited and comes with strict behavioural........

© Dawn Prism