At least three ships sailing from Iranian ports crossed the Hormuz Strait despite a US military blockade, but some vessels taking the route later turned back, maritime tracking data indicated on Tuesday.

They were among at least seven Iran-linked vessels that passed through the strait after Washington’s blockade came into effect at 1400 GMT on Monday, according to maritime data provider Kpler.

The Liberia-flagged bulk carrier Christianna crossed the strait after unloading 74,000 tonnes of corn at the Iranian port of Bandar Imam Khomeini in the Gulf, passing Iran’s Larak Island in the strait around 1600 GMT on Monday, Kpler data showed.

A second ship, the Comoros-flagged tanker Elpis, was near Larak Island around 1100 GMT and cleared the strait about 1600 GMT.

It was loaded with 31,000 tonnes of methanol, having left the Iranian port of Bushehr in the Gulf on March 31, Kpler data showed.

The tracker indicated that the other vessels that crossed included the Argo Maris, which had also sailed from Iran.

Maritime analysts have cautioned during the recent weeks of conflict around the strait that ships’ signals in the region have been disrupted and manipulated, making precise, comprehensive tracking difficult.

US says blockade intact

Iranian forces effectively closed the strait after the war broke out with US and Israeli strikes on Iran on February 28.

The US on Sunday announced its own blockade after peace talks with Iran failed.

The US military said on Tuesday its blockade had held and that it had stopped six vessels from sailing out of Iranian ports outside the Gulf during the first 24 hours.

“No ships made it past the US blockade, and six merchant vessels complied with direction from US forces to turn around to re-enter an Iranian port on the Gulf of Oman,” outside the strait, regional command CENTCOM said in a post on X.

It said the blockade was “being enforced impartially against vessels of all nations entering or departing Iranian ports and coastal areas, including all Iranian ports on the Arabian Gulf and Gulf of Oman.”

The Elpis’s AIS transponder signal appeared to go off at 2300 GMT on Monday after it crossed the strait, and its location on Tuesday could not be determined.

Chinese tanker turns around

A Chinese tanker, the Rich Starry, also crossed the strait overnight from Monday to Tuesday via the Iranian-approved vetting route south of Larak Island.

Kpler said that the vessel was carrying 31,500 tonnes of methanol and was bound for Sohar in Oman, according to data from its transponder.

It turned around while in the Gulf of Oman at around 1100 GMT on Tuesday and headed back up towards the strait, its destination unknown.

The Christianna turned around off Oman, where it was heading, at around 1500 GMT. Its new destination was also unknown.

The other vessels crossing were the bulk carrier Manali, which had traded with Iran in the past.

The other two were Iran-flagged ships: the container carrier Kashan, which is under US sanctions, and the Moshtari, a cargo ship that then went to an Iranian port on the strait.

The Rich Starry and Elpis are listed by the United States’ Office of Foreign Assets Control as being sanctioned for ties to Iran.