Traffic conditions in the Hormuz Strait ahead of President Trump's blockade declaration

The Hormuz Strait, one of the world’s most important shipping routes, remained essentially closed ahead of President Donald Trump’s declaration of a blockade. On April 7, Trump unexpectedly paused hostilities with Iran for two weeks in exchange for Iran opening the Hormuz Strait and for both sides to pursue peace negotiations. On April 12, after talks in Pakistan ended without an agreement, he announced that the U.S. Navy would blockade the Hormuz Strait.

U.S. blockade details

Later, CENTCOM said it would blockade all maritime traffic to and from Iran’s ports from 10:00 a.m. on April 13, Eastern Time. CENTCOM said the blockade would not impede ships entering or leaving ports not associated with Iran. The blockade would apply in part to vessels of all nations seeking to travel to or from Iranian ports and coastal areas, including Iran’s ports along the Persian Gulf and the Gulf of Oman, according to CNBC.

Fragile ceasefire and limited passage

Bloomberg reported that before these statements, the number of ships able to pass through the Hormuz Strait was already sparse, reflecting the fragility of the ceasefire. Iran’s continued control of Hormuz and tolls for ships passing through the strait were cited as factors preventing a peace agreement.

Vessel movements near the strait

On the morning of April 12 local time, after two other very large crude carriers entered the Persian Gulf, the VLCC Agios Fanourios I, while en route to Iraq, abruptly changed course just before entering the lane between Iran’s Larak and Qeshm islands, according to vessel-tracking data compiled by Bloomberg.

Initially, the Pakistani tankers Khairpur and Shalamar also turned, like the Agios Fanourios I. Khairpur later reversed again and continued through Hormuz. Shalamar also appeared to proceed through the Strait, according to data from intelligence firm Kpler.

Earlier that day, the supertanker Mombasa B had entered the Persian Gulf, per Bloomberg tracking data. From the morning of April 11, seven other vessels, including Iran’s Hilda I, had entered the area, while 11 vessels were observed leaving the strait over the same period, most connected to Iran or China.

Bloomberg noted that data collection on tankers is challenging because many ships switch off AIS to avoid tracking.

Observed routing patterns

From the observations, ships entering Hormuz between April 11–12 were confined to a narrow northbound lane between Larak and Qeshm. Some vessels exiting Hormuz used a narrow southern corridor along the Iranian coast near Larak.

Additionally, some ships departed Hormuz via a Tehran-approved coastal route near the southern shore of Larak.

Trump warning on payments to Iran

In a Truth Social post on April 12, Trump warned that the U.S. Navy would block any vessel that pays a fee to Iran and stated that no ship paying illegal fees would have safe passage on the seas.

Market impact and oil prices

The congestion at Hormuz—through which about one-fifth of global oil consumption passes before conflict—is creating a supply shock and pushing the world toward a significant energy crisis.

This morning, Brent and WTI crude prices both rose above $100 per barrel after briefly dipping below the level in the previous week.