Global oil markets are reeling after Iran declared the vital Strait of Hormuz “closed,” warning that any vessel attempting to pass could face “severe measures.”

Brent crude prices have surged above $110 per barrel-one of the highest levels since the escalation of U.S. military action-highlighting growing fears of a major supply shock, The Caspian Post reports via foreign media.

The Strait of Hormuz is a critical artery for global energy, carrying around 20% of the world’s oil and gas exports.

Meanwhile, US President Donald Trump has escalated pressure on Tehran, warning that failure to reopen the waterway could lead to strikes on Iran’s energy infrastructure. The warning follows Tehran’s rejection of a U.S.-backed proposal aimed at ending the conflict.