The Strait of Hormuz and modern maritime coercion

On the night of March 11, 2026, a Vietnam-flagged liquified gas carrier called the NV Aquamarine entered the Strait of Hormuz at approximately 21:30 GMT. After loitering in a strange triangular pattern near the strait's entrance, its tracking signal placed it southeast of Basra, on the border between Iran and Iraq, just sixty minutes later. To cover the distance of roughly 467 miles (~750 kilometres) that separated Basra from the Strait’s entrance in only an hour, the vessel would have had to travel at approximately the speed of a commercial aircraft.

The vessel had not, of course, moved at any such speed. It had simply lied about where it was.

NV Aquamarine GPS spoofing route. Credit: Pole Star Global.

Speaking to The Beiruter, Saleem Khan, Chief Data and Analytics Officer at maritime intelligence firm Pole Star Global, described the vessel’s behavior as a “tell-tale sign of spoofing,” in which ships deliberately falsify GPS location data to conceal their actual movements. As these types of vessels typically steam at 10 to 15 knots, he explained, the claimed movement was “physically impossible.”

The case of the NV Aquamarine, although particularly dramatic, is not an isolated incident. Since the outbreak of the U.S.-Israel-Iran war linked to Operation Epic Fury, which has thrust the Strait of Hormuz into the center of a sophisticated campaign of maritime disruption, intelligence firms have documented incidents involving GPS spoofing, electronic interference, disabled tracking systems, and suspicious vessel movements across the Persian Gulf and Strait of Hormuz.

According to Pole Star Global's Maritime Incident Monitor, 77 conflict-related events were recorded across the region between Feb. 28 and May 22, including direct strikes, vessel seizures, suspicious activity, and electronic interference linked to the conflict. Those incidents set 17 vessels ablaze, sank one ship, and killed at least 12 crew members. As seen in the monitor's map, dense clusters of activity now surround the narrow entrance to the strait itself, while blinking indicators track incidents recorded within the previous two weeks.

Maritime incidents across the Persian Gulf and Strait of Hormuz. Credit: Pole Star Global.

The disruption has already had major implications for global shipping patterns. Further data shared with The Beiruter shows vessel tanker traffic through the Strait of Hormuz collapsing from approximately 1,822 arrivals in January 2026 and 1,716 in February, to just 31 in March, 92 in April, and 35 through mid-May.

Collapse in tanker traffic through the Strait of Hormuz in 2026. Credit: Pole Star Global.

Beyond the immediate security risk, the disruptions have unfolded in open defiance of the framework governing international maritime passage. Under the United Nations Convention on the Law of the Sea, known as UNCLOS, strategic waterways used for international navigation fall under the transit passage regime, which states that coastal countries shall not hamper transit passage and that there shall be no suspension of transit rights through such corridors. 

“International maritime law enforcement requires a willingness from international nations to uphold the rule of law and international law, said Mark Nevitt, Associate Professor at Emory University School of Law and former attorney in the United States Navy.

We are witnessing a fundamental challenge to transit passage rights in the Strait of Hormuz that may have ripple effects around the world if they are allowed to deteriorate.

The stakes of that challenge extend well beyond the waterway itself. What the strait is now testing is not whether international maritime law is clear — it is — but whether it can remain effective when global commerce depends on legal norms that are technologically easier than ever to violate.

The law behind the Strait

Situated at the mouth of the Persian Gulf and separating Iran to the north from Oman to the south, the Strait of Hormuz serves as one of the world’s most strategically important maritime passages and a critical artery for global energy trade.

According to the International Energy Agency (IEA), approximately 20 million barrels of crude oil and oil products moved through the Strait each day in 2025, accounting for roughly a quarter of all globally traded oil transported by sea. The energy trade passing through Hormuz was valued at an estimated $600 billion annually in 2025, and the IEA described the resulting disruption as “the largest supply disruption in the history of the global oil market.” 

That geography has long made Hormuz a focal point of competing legal claims. As coastal states around the world expanded their territorial seas during the mid-20th century, concerns grew that some of the world's most critical maritime corridors could fall under near-complete national control. In the case of Hormuz specifically, Iran extended its maritime boundary claims in 1959, and Oman followed in 1972, effectively placing much of the Strait within their territorial waters despite the waterway being just 21 nautical miles wide at its narrowest point.

The negotiations that ultimately produced the United Nations Convention on the Law of the Sea, known as UNCLOS, in 1982 sought to resolve that tension. Under the treaty's transit passage regime, coastal states retained sovereignty over territorial waters reaching12 nautical miles from their coastlines, while commercial shipping retained a non-suspendable right of passage through major international straits.

Although neither Iran nor the United States formally ratified UNCLOS, that absence carries less legal weight than it might appear.

“That regime is now generally considered part of customary international law and to be binding on Iran even though it is not a party to UNCLOS,” said Douglas Guilfoyle, Professor at UNSW Canberra who specializes in international law and maritime security.

Guilfoyle noted that although coastal states retain certain rights, including regulating navigation for safety purposes and acting against vessels engaged in hostile conduct, those powers are limited to specific behavior during transit and do not include broader geopolitical retaliation or the suspension of ordinary commercial passage.

Even before UNCLOS, the 1958 Geneva Convention on the Territorial Sea, which Iran did ratify, recognized that straits used for international navigation could not be arbitrarily closed. Under that earlier framework, foreign vessels enjoyed what was known as “non-suspendable innocent passage.” UNCLOS later strengthened those protections further through the transit passage regime.

For decades, that legal framework helped underpin global maritime trade by ensuring that major shipping corridors remained open even during periods of geopolitical tension.

Modern maritime coercion

The crisis unfolding around Hormuz demonstrates how maritime coercion has expanded beyond conventional naval confrontation into forms of disruption that blend technology and commercial pressure.

Iran has made that plain, taking measures ranging from publicly threatening to levy tolls and fees to permitting free transit only for a select group of “friendly” nations.

Iranian lawmakers have also moved to codify expanded authority over movement through the Strait via the creation of the Persian Gulf State Authority in early May. Shortly after its formation, the body published new maritime jurisdiction boundaries asserting regulatory authority over broad sections of the Strait, including waters that the UAE and Oman regard as part of their own sovereign territory, while announcing that vessels transiting the area would require permits issued by the authority.

Natalie Klein, a professor at UNSW Sydney’s Faculty of Law and Justice specializing in maritime law, noted that disputes surrounding transit passage often become legally contested because states frame restrictions as matters of security or navigational safety rather than interference with lawful passage.

“The difficulty is that the thresholds or the standards may allow for different interpretations,” Klein said.

What one state claims is an impairment or denial of passage, another state may argue is ensuring navigational safety.

Yet despite competing state assessments, Guilfoyle emphasized that international law still distinguishes between targeted enforcement measures and outright closure.

“There remains a significant distinction between measures directed at particular vessels for security reasons and an attempt to ‘close’ the strait to all maritime traffic generally,” he said.

Even so, modern maritime pressure often operates below the threshold of formal blockade.  Guilfoyle noted that states can still exert substantial pressure on commercial transit through tactics that stop short of universally denying passage.

These measures can include boarding and inspection operations conducted under disputed security or environmental justifications, aggressive naval maneuvering, GPS jamming or electronic interference, harassment by patrol craft, uncertainty surrounding mine or missile threats, selective vessel detention, or insurance-risk escalation triggered by military incidents. Even political rhetoric alone can significantly alter commercial behavior if shipowners and insurers conclude the security environment has become unstable.

“In practice, states rarely need to formally close a strait in order to disrupt shipping,” Guilfoyle said.

There are many forms of what might be called ‘grey-zone’ maritime coercion.

The Pole Star Global data suggests those tactics are already having substantial commercial effects. Although international law continues protecting transit passage through Hormuz, shipping companies, insurers, and governments have already begun reorganizing routes around mounting operational risk.

At the same time that tanker traffic through the strait collapsed, crude oil tanker movements through the Suez Canal climbed from 251 in January to 283 in March and 302 in April, according to Pole Star’sPort and Zone Arrival data. Khan attributed the shift to Saudi Arabia’s reopening of the East-West pipeline, which moves crude overland from the Eastern Province to the Red Sea port of Yanbu, bypassing Hormuz entirely. The legal right to transit Hormuz remains intact. The commercial reality, however, is that the world has already begun routing around it.

Rising crude oil tanker traffic through the Suez Canal following disruptions in Hormuz. Credit: Pole Star Global.

Asymmetry and a stress test of maritime law

Military analysts have long argued that Iran does not need to defeat the U.S. Navy or its regional partners outright in order to generate severe economic disruption.

The geography of Hormuz makes that calculus particularly stark. Because the waterway reaches depths of only about 200 feet at its narrowest point, the Strait is especially vulnerable to naval mining. According to the U.S. Defense Intelligence Agency, Iran possesses approximately 5,000 naval mines – weapons capable of generating severe economic disruption without requiring direct naval confrontation.

The asymmetry is stark, Nevitt warned, as a naval mine costing mere thousands of dollars to deploy can disrupt shipping flows worth billions

That imbalance has become more concerning as the U.S. Navy transitions away from older mine countermeasure vessels. Last year, the Navy decommissioned half of its Avenger-class mine countermeasure ships and began replacing them with Littoral Combat Ships equipped with anti-mine capabilities. Unlike the Avenger-class vessels, which had a long battle-tested record, the newer systems have not yet been deployed in combat.

The challenge extends beyond military vulnerability alone. Unlike the full-scale naval blockades of earlier eras, technological disruption now allows states to exert pressure through selective interference capable of destabilizing commercial transit.

The implications are not limited to the Persian Gulf. The same transit passage regime governing Hormuz also applies to international straits such as the Strait of Malacca, the Bab el-Mandeb, and the Taiwan Strait, waterways that collectively underpin enormous portions of global trade and energy transit.

In that sense, the crisis surrounding Hormuz is testing more than the security of a single shipping corridor. The modern maritime legal order was designed to prevent states from physically sealing off the world's most important waterways. What the current crisis is demonstrating, however, is that technology has lowered the threshold for effective closure well below what the law was designed to address.

“The Strait of Hormuz is a good example of an environment in which law remains an important geopolitical consideration,” Guilfoyle said, “but is not necessarily decisive on its own.”