For the first time since the Iran conflict: Japanese oil tanker reportedly successfully passes through the Strait of Hormuz

An ultra-large crude oil tanker associated with Japanese refiner Idemitsu Kosan reportedly succeeded in passing through the Strait of Hormuz, becoming the first Japanese oil tanker to successfully sail out of the Persian Gulf since the United States and Israel took military action against Iran. This marks a significant shift in energy supply strategy for Japanese refiners and shipowners.

According to several media reports, the "Idemitsu Maru," fully loaded with 2 million barrels of Saudi crude, departed northwest of Abu Dhabi on Monday night, took a route approved by the Iranian government, and successfully passed through the strait on Tuesday. LSEG shipping data confirmed the smooth passage, and the vessel is currently reported to be heading to Nagoya, Japan, with an expected arrival on May 18.

This passage occurred against the sensitive backdrop of a US military blockade of Iranian ports, with shipping volume through the strait dropping to nearly zero. According to Kpler and SynMax data, before the Iran conflict began, about 125 to 140 vessels crossed the Strait of Hormuz daily, but only 7 were recorded in the past 24 hours. The “Idemitsu Maru” transit is also one of the largest attempts since the US began its maritime blockade of Iran two weeks ago.

Media citing tanker tracking data report that after more than a week anchored northwest of Abu Dhabi, the “Idemitsu Maru” set sail for the Strait of Hormuz on Monday night. The vessel chose the northern route near Qeshm and Larak Islands—specifically, the path permitted by Tehran—and completed the crossing on Tuesday.

Independent data from MarineTraffic showed “Idemitsu Maru” located approximately 30 km east of Larak Island, heading east with its automatic identification system (AIS) enabled.

The “Idemitsu Maru,” built in 2007 and registered under the Panama flag, is a very large crude carrier (VLCC) operated by Idemitsu Kosan’s tanker division. The 2 million barrels of crude onboard were loaded at Saudi Arabia’s Juaymah terminal in early March this year. The tanker entered the Persian Gulf just days before the US and Israel attacked Iran in late February.

An Idemitsu Kosan spokesperson said on Tuesday that, for security reasons, the company would not comment on individual vessels.

It is worth noting that due to some vessels turning off their transponders and signal disruptions in the region, tracking data for ships in the Strait of Hormuz may not reflect all crossings.

Reports indicate that before the “Idemitsu Maru” crossed the Strait of Hormuz, Japanese refiners and shipowners exercised extreme caution due to the conflict. Refineries such as Idemitsu Kosan had primarily relied on ship-to-ship transfers outside the Persian Gulf to receive some cargo, while also turning to alternative US supplies using smaller tankers.

Media point out that before the US-Iran conflict erupted on February 28, causing disruption to Middle East crude oil and LNG supplies, about 95% of Japan’s oil imports came from the Middle East, most of which were transported via the Strait of Hormuz.

During the war, other Japan-related vessels reportedly did pass through the Strait of Hormuz, but only to transport other goods.

Reports indicate that earlier this month, a LPG (liquefied petroleum gas) carrier co-owned by another Japanese shipowner transited the strait with Indian assistance. The Sohar LNG carrier, jointly owned by Mitsui O.S.K. Lines (MOL), as well as the Green Sanvi LPG carrier owned by Mitsui & Co., have also recently completed the crossing.

The successful transit of the “Idemitsu Maru” marks one of the largest such transits so far.

The passage of “Idemitsu Maru” comes as the US continues to enforce a maritime blockade on Iran during the US-Iran ceasefire, a measure the Iranian side sees as a major obstacle to launching new negotiations with the US.

According to Xinhua News Agency, US Central Command stated on Tuesday the 28th that US forces boarded and inspected a container ship called "Blue Star 3" in the Arabian Sea, suspecting it was trying to sail to Iran and violate the US blockade of Iranian ports. After confirming that the ship’s route did not include Iranian ports, it was released. According to CCTV News, US Central Command reported the same day that, since the blockade began, a total of 39 ships have changed course at the US military's request so far.

The Iranian side continues to send tough signals. According to CCTV, the deputy commander of the Islamic Revolutionary Guard Corps Navy said on the 28th that Iran has achieved “absolute control” over the Strait of Hormuz, requiring passage fees from transiting vessels, mandating the use of Persian for foreign ships’ communication when passing, and stressing that “without the Supreme Leader's order and the will of the people, Iran will never allow even a drop of oil to flow out of the strait.”

According to CCTV News, Iran’s permanent mission to the United Nations also issued a statement on the 28th, asserting that as the main coastal nation of the territorial waters where the Strait of Hormuz is located, Iran has the right to take necessary and reciprocal measures in response to security threats, accusing the US of “illegal actions” that endanger safety of international navigation, and emphasizing that any consequences of obstructed transport in the Persian Gulf region must be borne by the US.