イラン・米国によるホルムズ海峡封鎖：タンカー、緊張、そして代理戦の構図

No new incidents involving U.S. or Iranian forces have been reported in the Gulf of Oman or the Strait of Hormuz since the Hell‑fire missile strike on the Palau‑flagged Lian Star on June 13. The latest official statements from U.S. Central Command and the IRGC Navy, released on June 13, remain unchanged: the United States continues to enforce a maritime exclusion zone around the strait, while Iran maintains its closure order and warns that any vessel attempting to transit will be targeted.

A development would be any of the following: a confirmed missile, drone, or small‑arms attack on a commercial or military vessel; the boarding, seizure, or disabling of a tanker by either side; a new declaration from Tehran or Washington altering the status of the strait—such as a partial reopening, an extension of the blockade, or a diplomatic overture; the release of additional video or satellite evidence showing combat actions; or statements from regional governments (e.g., Oman, the United Arab Emirates, India) indicating casualties, rescues, or changes to their navigation advisories.

In the absence of fresh reports, the situation remains a stalemate. Both sides continue to cite the other’s actions as justification for maintaining their respective maritime postures, and commercial shipping companies are still navigating the heightened risk environment by seeking alternative routes or awaiting further guidance from the newly created Persian Gulf Strait Authority. Until new evidence emerges, the daily log will reflect the ongoing impasse without additional incidents.

June 13 2026 – US missile strikes on commercial tankers intensify; Iran closes the Strait of Hormuz

U.S. Central Command confirmed that on June 13 a Hell‑fire missile struck the Palau‑flagged tanker Lian Star in the Gulf of Oman, the latest precision strike aimed at vessels it says are attempting to breach a naval blockade of the Strait of Hormuz. The attack followed a series of similar engagements, including a June 10 missile strike on the Palau‑flagged MT Maravex that ignited a fire and required the rescue of all 24 Indian crew members, and a June 9 fighter‑jet‑launched munition that disabled an oil tanker bound for Iran after the crew ignored repeated commands.

The U.S. has justified the strikes as enforcement of sanctions and an effort to prevent Iranian oil from reaching international markets. Video released by the Navy on June 12 showed the Hell‑fire missile impact on an India‑linked tanker, and a separate clip posted by the Pentagon depicted the disabling of the Lian Star. In each case, U.S. officials said the vessels had either entered a designated exclusion zone or attempted to run the blockade.

Iran’s Islamic Revolutionary Guard Corps (IRGC) responded by announcing a full closure of the Strait of Hormuz on June 11, citing the “U.S. blockade” as an act of aggression. The IRGC Navy warned that any ship attempting to transit the waterway would be targeted, and it invoked the newly created Persian Gulf Strait Authority—established in May—to regulate traffic and impose fees. Iranian officials also threatened retaliation against U.S. bases in the region, echoing earlier statements by Mojtaba Khamenei that warned of a broader war front if the United States continued its maritime operations.

The escalation has drawn diplomatic protests. India summoned a senior U.S. diplomat on June 12 after three Indian sailors were killed in the June 10 strike on the Maravex and additional crew members were reported missing following the June 13 attack on the Lian Star. Indian officials called for an immediate halt to U.S. strikes on commercial vessels and urged Washington to respect the safety of its nationals. The United Kingdom and the United Arab Emirates have also issued statements urging restraint, while the United Nations has called for both parties to avoid actions that could further jeopardize the free flow of oil through the strait.

In the meantime, commercial traffic remains severely disrupted. Iranian authorities reported that, despite the closure, a limited number of vessels—primarily those with explicit permits from the IRGC‑controlled authority—have been allowed to pass under strict supervision. However, satellite imagery and AIS data indicate a sharp decline in transits compared with the pre‑crisis average of 35 ships per day recorded in late May.

U.S. officials maintain that the blockade is legal under international law, pointing to United Nations Security Council resolutions that authorize interdiction of vessels carrying sanctioned Iranian oil. Critics argue that the repeated use of precision missiles against civilian‑flagged tankers risks violating the principle of proportionality and could be deemed an unlawful use of force.

The situation remains fluid, with both sides signaling a willingness to intensify military posturing. Analysts note that any miscalculation—particularly a direct engagement between U.S. warships and IRGC naval units—could trigger a broader regional conflict, underscoring the strategic importance of the Hormuz corridor for global energy markets.

US Navy Disables Iranian Tankers as Gulf Tensions Rise

June 2, 2026 — The United States Navy disabled three Iranian tankers in the Gulf of Oman on June 1, prompting the Islamic Revolutionary Guard Corps to threaten massive retaliation and warn of opening new war fronts, according to statements from IRGC officials and US defense officials.

The naval engagement marks the most significant direct combat between US and Iranian maritime forces since the Hormuz crisis escalated in late April. IRGC Navy spokesman Admiral Ali Raza Tangsiri issued a statement vowing to target American military installations across the region, the semiofficial Fars News Agency reported. The threat followed a video message from Supreme Leader Ayatollah Ali Khamenei's son, Mojtaba Khamenei, who warned of retaliation and predicted Israel's collapse following what he described as US aggression in the Gulf.

President Donald Trump confirmed the US strikes in a post on social media, writing that American forces "had no choice" after Iranian vessels attempted to breach what the administration has described as a lawful naval interdiction operation. The White House has maintained that US operations in the strait are enforcement of sanctions targeting Iranian oil exports.

The June 1 strikes came as US-Iran ceasefire negotiations over the broader Iran-Israel conflict appeared to stall over the issue of Strait of Hormuz access. Iran has insisted any agreement include guarantees of unimpeded commercial transit through the waterway, which carries roughly one-fifth of the world's daily oil supply. Washington has refused to accept what it characterizes as preconditions.

Earlier in the week, Trump threatened action against Oman, which borders the Strait of Hormuz, accusing Muscat of failing to prevent Iranian military operations emanating from its territory. The threat, which raised concerns among regional trading partners, drew condemnation from Oman and further complicated diplomatic efforts.

The IRGC separately reported June 1 that 25 to 26 ships had transited the strait in the preceding 24 hours, including oil tankers engaged in energy trade. The figure marks a slight increase from previous days but remains far below normal traffic levels, reflecting ongoing reluctance among major shipping insurers and operators to risk passage through contested waters.

Iran's Revolutionary Guard Corps has issued a new navigation advisory demanding all vessels coordinate with Iranian military headquarters before entering the Strait of Hormuz, warning that ships entering without authorization will face potential attacks, according to statements from the IRGC Navy reported May 4.

The directive, which included the release of a new map outlining zones under IRGC control, comes amid a fresh wave of competing claims between Tehran and Washington over incidents in the narrow waterway. The UAE separately accused Iran of striking an oil tanker in the strait on May 4, marking the first allegation of damage to a third-party commercial vessel since the escalation began.

President Donald Trump announced May 4 that the United States would resume what he called "Hormuz War" operations after what administration officials described as Iranian missile strikes targeting American warships in the strait. The IRGC separately released statements declaring itself the sole "guardian" of the waterway, a framing Iranian officials have used to reinforce claims of sovereign control over the passage that carries roughly one-fifth of the world's daily oil supply.

The competing narratives could not be independently verified. The White House provided no immediate evidence supporting the missile strike claims, while Iranian officials denied targeting US naval vessels. The exchange marks the most direct military posturing between the two sides since the strait's closure was announced April 18.

Global oil markets climbed further May 4, extending the four-year high reached May 3 following reports that Iran's oil production had declined under the combined effect of the US naval blockade and IRGC restrictions on tanker transits. Brent crude rose 2.3 percent in Asian trading before pulling back on uncertainty surrounding the actual extent of disruptions.

India, whose flagged vessels have been targeted twice since mid-April, summoned Iran's ambassador for the second time in two weeks to demand guarantees for the safety of its mariners. European Union foreign policy chief Kaja Kallas called for an emergency video conference of senior diplomats later May 4 to discuss de-escalation options, according to a statement from the bloc's diplomatic service.