Iran's state media claimed Wednesday morning that a bulk carrier transporting food supplies and an Iranian crude oil tanker had entered Iranian waters after transiting the Strait of Hormuz, hours after a top U.S. military commander said a blockade of Iranian ports was "fully implemented."

Iran's Fars News Agency said a supertanker capable of transporting 2 million barrels of oil had sailed through international waters and the Strait of Hormuz with its tracking system switched on, "without any concealment."

Data from the ship tracking website MarineTraffic.com show a number of vessels, including the crude oil tanker Alicia, making the journey through the strait overnight. The Chinese-owned Alicia has previously called at Iranian ports and was sanctioned under a previous name for carrying Iranian crude oil. 

The Alicia was heading toward the Persian Gulf and reached the coast of Oman on Saturday, the day before the blockade was announced. It appeared to alter its course in the Gulf of Oman when the blockade began, but then continued through the Strait of Hormuz overnight Tuesday, along with at least two other oil tankers.

Two Iran-flagged container ships, both subject to U.S. sanctions, also appeared to leave the Persian Gulf Tuesday and were continuing to sail close to Iran's south coast Wednesday. 

The U.S. blockade, which came into effect on Monday, is 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," CENTCOM said Sunday.

U.S. "forces will not impede freedom of navigation for vessels transiting the Strait of Hormuz to and from non-Iranian ports," the military said.

On Wednesday, a U.S. official told CBS News that the blockade does not apply to sanctioned vessels unless they're entering or departing Iranian ports. It is being enforced from the Gulf of Oman, which means some vessels departing from Iranian ports could make it through the Strait of Hormuz, but the U.S. military intends to prevent them from getting much further than that, the official said.

It was not clear from the MarineTraffic data whether the Alicia or any of the sanctioned vessels had docked at Iranian ports since the U.S. blockade came into effect. At least two vessels have turned off their transponders in recent days near Iran's coastal waters, making them effectively invisible to open-source tracking services like MarineTraffic.

A CBS News analysis of ship tracking data from earlier this week appeared to show a number of other Iran-linked ships passing through the Strait of Hormuz in the hours after the blockade began on Monday.

One ship that crossed the strait after the blockade began on Monday — the Christianna — had previously stopped at the Iranian port of Bandar Imam Khomeini, at the far northern end of the Persian Gulf, tracking data show.

The Murlikishan, which is under U.S. sanctions over its connections to Iran, journeyed west through the strait overnight Monday, tracking data showed, along with another tanker, the Peace Gulf, which is not sanctioned by the U.S. but made a port call in Iran in December 2025.

The Rich Starry, a tanker sanctioned under a different name by the U.S., also sailed through the strait overnight Monday, while the Elpis, another sanctioned tanker, sailed through the strait after the blockade began, having apparently come from the Iranian port of Bushehr, according to tracking data.

Later Monday, ship tracking data showed the Rich Starry turning around, going back into the Strait of Hormuz and then turning its transponder off as it approached Iran's Qeshm Island. On Tuesday, the Elpis stopped broadcasting its location near where the Rich Starry turned around.

CBS News cannot confirm that the ships have not been broadcasting false location reports — a practice called spoofing — to conceal their true whereabouts. It is also possible for a ship to broadcast that it is heading to one destination but for it to travel to a different port.

CBS News also cannot confirm the exact location of the blockade.

Three additional tankers, all of which are sanctioned, appeared positioned Wednesday morning to travel through the strait into the Persian Gulf.

"A blockade of Iranian ports has been fully implemented as U.S. forces maintain maritime superiority in the Middle East," Adm. Brad Cooper, CENTCOM Commander, claimed in a statement shared online late Tuesday. "An estimated 90% of Iran's economy is fueled by international trade by sea. In less than 36 hours since the blockade was implemented, U.S. forces have completely halted economic trade going into and out of Iran by sea."