Iran’s Islamic Revolutionary Guard Corps declared the Strait of Hormuz closed to commercial vessels of all nationalities on October 17, 2026, the most explicit assertion yet in a campaign that has driven attacks on oil tankers to their highest weekly total since the US-Israel war on Iran began in late February. Eleven tankers were attacked while transiting the strait in the week ending October 4, the most strikes on commercial shipping since the war began, according to International Maritime Organization data. Five more tankers came under fire the following week, and twelve sailors were injured when a projectile struck their vessel in the strait.
Commercial transits through the waterway have collapsed to a fraction of pre-war levels, with IMF PortWatch recording just two vessel crossings on October 11 against a pre-crisis baseline of roughly 85 per day, according to maritime tracking data reviewed this week.
Wartime High in Tanker Strikes
The surge in attacks comes nearly eight months into a conflict that began on February 28, 2026, when the United States and Israel conducted airstrikes on Iranian military targets, prompting Tehran to close the strait to foreign shipping. The IRGC confirmed on March 2 that the strait was closed to vessels from “unfriendly nations,” allowing only Iran-approved ships to pass, and claimed complete naval control of the waterway two days later. Several Iran-approved tankers, mostly bound for China and India, continued transiting during the conflict, some under military escort.
Maritime tracking firm Kpler recorded ten tankers struck in the strait between September 28 and October 4, followed by another strike on October 5. The UK Maritime Trade Operations centre separately logged 15 attacks between October 6 and 14, with 11 occurring in just four days, including a container ship and a tanker hit by unknown projectiles.
Transit Volumes Collapse, Oil Markets React
Before the war, the Strait of Hormuz typically handled about 125 large commercial vessels a day, with shipments through it accounting for roughly 20 percent of global crude oil and LNG supplies. Crude oil exports from the Middle East had rebounded in September to prewar levels, aided largely by the US military escorting ships through Hormuz along a route hugging Oman’s coast, before the fresh wave of attacks began in late September.
Brent crude stood at $109.06 a barrel, up 0.57 percent over 24 hours as of this week, reflecting continued market tension over the chokepoint’s status. The US military has said that 97 percent of ships continue to transit safely despite Iranian attacks, though the figure has not been independently verified by other outlets covering the conflict.
Diplomatic Standoff Over Reopening
On October 17, the IRGC Navy announced that passage of commercial vessels of all nationalities through the strait was prohibited. Hours later, the Guard said a supertanker carrying more than two million barrels had struck a mine after allegedly switching off its radar and using an unauthorized route; the vessel’s identity, flag and cargo owner have not been independently confirmed.
Iran’s foreign minister has said a seven-day plan to reopen the strait remains on the table, conditional on the United States meeting Tehran’s terms. Iranian Parliament Speaker Mohammad Bagher Ghalibaf has said the strait will not reopen until Iran’s seven conditions, based on the Islamabad memorandum, are satisfied.
Why it matters
The closure of one of the world’s most critical chokepoints, through which roughly a fifth of global oil and gas once flowed, is forcing tankers onto longer, costlier routes and keeping insurance and freight costs elevated worldwide. Continued attacks on commercial vessels raise the risk of wider regional escalation and threaten crew safety along a shipping lane with few practical alternatives. Energy markets remain on edge pending any diplomatic breakthrough, with a full resumption of transits likely to take weeks even if a deal is struck, given the need for mine clearance and insurer reassurance.
Source: CNBC
