Brent crude futures climbed above $75 a barrel on Monday, driven by reports that the United States has reimposed a naval blockade against Iranian vessels in the Strait of Hormuz.
The move marks a sharp reversal in the diplomatic trajectory between Washington and Tehran, following a weekend of trading strikes and conflicting claims over the status of shipping lanes in the critical waterway.
President Donald Trump announced the reinstatement of the blockade, citing the need to secure the strait amid ongoing hostilities.
The decision effectively ends the fragile calm that had begun to settle over the region after earlier de-escalation efforts.
Markets reacted swiftly to the news, with energy prices reflecting the renewed risk of supply disruption in a corridor that handles roughly a fifth of global oil consumption.
The escalation comes just weeks after the U.S. and Iran agreed on a 60-day roadmap for a peace deal, a development that had previously helped evaporate the war premium in oil prices. That optimism was short-lived, as tensions flared again following attacks on commercial ships in the strait.