Iran has declared the Strait of Hormuz closed to all maritime traffic until further notice, following a military strike on a vessel attempting to transit an unapproved route on Saturday night.
The announcement by the Iranian regime marks a sharp escalation in regional tensions, effectively halting commercial shipping through the narrow waterway that handles roughly a fifth of the world's oil supply.
Tehran warned that any attempt by adversaries to use the incident as a pretext for attack would be met with a "severe response," signaling a hardline stance amid ongoing diplomatic friction with the United States.
The move immediately casts a shadow over global energy markets, where traders had begun to price in a potential de-escalation following the brief resumption of flows earlier this week.
With the chokepoint now officially shut, the risk premium on crude oil is likely to surge as supply disruption fears return.
Brent crude, which had risen in recent sessions on stalled ceasefire talks, faces renewed upward pressure as the prospect of a prolonged closure looms.