A Japanese oil tanker operated by Idemitsu Kosan passed through the Strait of Hormuz between April 28 and April 29, 2026 [1].
The transit follows a period of regional tension and a significant delay for the vessel. The event serves as a diplomatic signal between Tehran and Tokyo as Japan seeks to maintain stable energy supplies from the Persian Gulf.
The tanker, identified as the 出光丸 (Idemitsu Maru), completed its passage after a 62-day delay since its previous transit of the strait [3]. Reports on the exact timing vary, with some sources stating the vessel entered the strait on the evening of April 28 [1], while others indicate it passed in the early hours of April 29 [2]. Before entering the strait, the ship performed a 90-degree turn [3].
Iran's ambassador to Japan said the event was a "sign of long-standing friendship" [1]. The ambassador linked the gesture to the 1953 Nisshōmaru incident, which occurred 73 years ago [1]. By allowing the tanker to proceed, Iran framed the move as a diplomatic gesture based on historic goodwill [1].
Japan's interest in the passage centers on securing oil supplies amid volatility in the region [4]. The Strait of Hormuz remains the primary artery for oil exports from the Persian Gulf to the Gulf of Oman [4].
Former U.S. President Donald Trump commented on the situation via social media. According to one report, he posted "もういい人はやめます" [2]. However, other reports said Japan should secure the Hormuz Strait itself [4].
“"sign of long-standing friendship"”
The release of the Idemitsu tanker suggests a tactical use of maritime access by Iran to reward diplomatic alignment. By invoking the 1953 Nisshōmaru incident, Tehran is leveraging historical narratives to strengthen bilateral ties with Japan, potentially creating a diplomatic wedge between Tokyo and the US regarding the security of the Strait of Hormuz.
