Iran is preparing to widen its sanctionable shipping zone near the Strait of Hormuz just as its officials warn Washington that further strikes will trigger a far heavier retaliation. According to Reuters, Iran's top security official said the zone will be announced within days, and any ship entering the area will be added to a sanctions list.

Mohsen Rezaei, secretary of Iran's Supreme National Security Council, said the restricted zone would begin from the line of the US Navy's blockade and extend into parts of the Gulf, according to state media. Maps of ship passage through Hormuz, agreed with Oman, are due to be signed in the coming days. The strait, which separates Iran from Oman at the mouth of the Gulf, is the world's most important oil transit chokepoint.

The move comes alongside a sharper rhetorical warning from Tehran. Parliament Speaker Mohammad Baqer Qalibaf said the rules of the game had changed, telling the US that any future attack on Iran's interests and security "will receive a faster, heavier and more painful response."

The comments follow a fresh round of hostilities. US Central Command said it struck three Iranian vessels, including one off Kharg Island, after Iran's Revolutionary Guard Corps fired ballistic missiles at two US Navy ships.

Six months into the conflict, the situation remains at a stalemate. A preliminary ceasefire reached in June has unravelled, and diplomatic efforts to revive it have made little progress. Strikes paused for much of August before resuming in recent days.

Iran retains the capacity to threaten US interests in the region and to further restrict flows through Hormuz, a corridor that carried a fifth of global oil supply before the war. US officials maintain that enforcement of Washington's own blockade is holding: Energy Secretary Chris Wright said transits through the strait are averaging more than 9 million barrels a day, putting flows at roughly two thirds of pre-conflict levels once alternative pipeline routes are included. Those alternatives include overland pipelines that bypass the strait, such as Saudi Arabia's East-West pipeline to Red Sea terminals and the UAE's pipeline to the port of Fujairah on the Gulf of Oman, which have absorbed some traffic during the conflict.

The planned restricted zone adds a fresh layer of shipping risk to the Hormuz corridor. Any expansion of sanctionable shipping areas raises the prospect of further disruption to tanker traffic and insurance costs, even as US officials maintain that transit volumes remain close to two thirds of pre-war levels. The explicit threat of a "faster, heavier and more painful" response to further attacks keeps a geopolitical risk premium embedded in oil prices, particularly given the string of tit-for-tat strikes since the weekend. Traders will watch for the zone's actual coordinates and enforcement mechanism once published, since the scale of any premium depends on how much additional shipping area is affected.

Despite the US holiday Monday, Globex will open for oil trade at 6pm US Eastern time Sunday, which is 2200 GMT. Early FX rates often give an early indication of changes in sentiment regarding weekend news flow. So far trading is relatively calm despite the rhetoric from Iran: Monday open indicative forex prices, 07 September 2026 and Iran warns of tougher response: Oil, gold and stocks to watch over the holiday weekend.

Whether Iran's new zone meaningfully adds to pressure on shipping will depend on its precise boundaries and how strictly it is enforced once published — details that were not yet available at the time of the announcement.