Iran’s newly created Persian Gulf Strait Authority (PGSA) has announced the full closure of the Strait of Hormuz “until further notice,” marking a sharp escalation in the confrontation between Tehran and Washington. The move, confirmed on Thursday by Iranian state media, comes after a second consecutive night of US strikes on Iranian positions and a wave of Iranian retaliatory attacks. The PGSA, established only last month to impose a new transit protocol, stated that the waterway would be shut to all vessels due to “tensions created by the aggressive US forces in the region.” Ship captains who had already received transit permits were told to “wait patiently for further guidance.”

The declaration ended what had already become a severely constricted passage. According to several studies, maritime traffic through Hormuz—through which nearly a fifth of global oil supply passes—had plummeted from about 120 crossings per day to roughly 60 during April, a consequence of unilateral US restrictions and mounting insecurity. The closure now effectively halts all commercial movement, raising immediate alarm in energy markets and among maritime insurers. Tehran had previously allowed a trickle of shipments, limited to allied nations or vessels meeting strict conditions, but the new order withdraws even that calibrated access.

The tightening of the choke point was punctuated by a series of violent exchanges. State media in Iran said that a US projectile struck a 150-tonne dhow carrying “essential goods” from the Omani port of Khasab to the Iranian city of Sirik, approximately five nautical miles from Khasab. All five crew members were rescued by passing boats and taken to Oman. These incidents unfolded alongside overnight strikes by both sides—the fourth round in a week—with Iran admitting it had launched attacks targeting unspecified locations, while the US military focused on what it called Iranian military infrastructure.

Following the closure order, the Islamic Revolutionary Guard Corps claimed to have fired on two vessels attempting to cross the strait, underscoring Tehran’s willingness to enforce its edict. Observers in European capitals warned that any miscalculation could rapidly draw in other Gulf states or trigger a more forceful NATO naval response. Diplomats in Brussels and London are scrambling to revive back-channel communications, but officials acknowledge that the window for de-escalation is narrowing. The PGSA’s abrupt assumption of authority—bypassing traditional maritime channels—adds a layer of legal ambiguity, complicating any international response.