NYT: Vessels sailed 'dark' with AIS off to evade Iranian detection

Ships navigate the Strait of Hormuz. [Reuters]
Ships navigate the Strait of Hormuz. [Reuters]

About 70 merchant vessels have transited the Strait of Hormuz over the past three weeks with US military guidance, sailing with their automatic identification systems switched off, as Iran's blockade of the waterway drags on.

The New York Times reported May 31, citing anonymous US officials, that US Central Command (CENTCOM) has been supporting the passage of some commercial ships through the strait in recent weeks.

According to the report, the US military did not deploy warships to escort the vessels directly but maintained continuous communication with them to guide them along safe routes. Through that effort, roughly 70 ships successfully transited in and out of the Persian Gulf.

Most vessels made the crossing using what is known as "dark sailing" — cutting both their AIS transponders and running lights to avoid detection by Iran, which in effect controls the strait.

Sailing without AIS makes it difficult for ships to track one another's positions, forcing reliance on radar and significantly raising the risk of collision while demanding a high level of navigational skill.

US officials declined to disclose specific routes or vessel types but said at least some ships traveled while keeping their distance from the Iranian coastline.

Shipping analysts believe the US-guided vessels used routes closer to the Omani coast rather than the Iranian shore.

Washington has assessed that ships passing near the Iranian coastline without Tehran's authorization face a heightened risk of drone or missile strikes.

CENTCOM spokesperson Tim Hawkins told The New York Times that while the US military is not providing direct escorts, it is "continuously communicating and cooperating with commercial vessels seeking to transit the Strait of Hormuz freely and safely."

The US military assistance shows that limited transit through the strait is still taking place despite Iranian threats.

However, the volume remains a fraction of pre-war levels — averaging just three ships a day. Before the United States and Israel struck Iran in late February, more than 100 vessels used the strait daily, underscoring how far the waterway remains from any return to normalcy.

The strait is a critical energy corridor through which roughly 20 percent of the world's seaborne crude oil and liquefied natural gas passes. Since Iran's blockade disrupted global energy supply chains, the United States and the international community have focused heavily on restoring normal transit.

End-of-war negotiations between Washington and Tehran are said to be entering their final stages, but the two sides remain far apart on the question of who controls the strait.

The United States argues that the Strait of Hormuz, as an international maritime passage, must remain freely open to all — as it was before the war.

Iran, by contrast, is seeking to institutionalize its influence over the strait as a result of the conflict. Through the newly established Persian Gulf Strait Authority (PGSA), Tehran is pursuing plans to levy transit fees of up to $2 million per vessel. The perception that Iran has effectively secured control of the Strait of Hormuz is already spreading across the Middle East.

In response, the Treasury Department's Office of Foreign Assets Control placed the PGSA on its sanctions list on May 27, a move widely interpreted as Washington's refusal to recognize Iran's unilateral attempt to impose transit fees and assert administrative authority over the strait.

Experts, however, caution that even if the United States and Iran reach an agreement to reopen the strait, shipping traffic is unlikely to recover quickly to pre-war levels.

Just as vessel traffic through the Red Sea has yet to fully recover more than two years after Houthi attacks began disrupting it, shipowners are expected to remain cautious about resuming operations — weighing the risk of renewed conflict, tighter Iranian control, and potential exposure to US sanctions.

Western shipping companies are particularly concerned that any future cooperation with Iran's Islamic Revolutionary Guard Corps or affiliated bodies in transiting the strait could expose them to US sanctions.

As a result, some in the shipping industry are raising the possibility that the Strait of Hormuz may no longer function as the freely navigable waterway it once was, but instead emerge as a new kind of strategic maritime chokepoint where access is determined by political interests.


mokiya@heraldcorp.com