Brent crude oil prices surged 5% to $78 a barrel on Wednesday as escalating tensions in the Middle East fueled concerns over further supply disruptions.
President Trump said that as far as he is concerned, the ceasefire is over while the US launched strikes on Iran and revoked a waiver that had allowed the country to sell crude.
The actions followed a series of recent attacks on vessels transiting the Strait of Hormuz, including a Qatari LNG carrier and a Saudi oil tanker.
Tehran also said it had targeted 85 US military sites in Bahrain and Kuwait in response to what it described as US violations of the ceasefire.
The renewed conflict raised the prospect of fresh disruptions to global energy supplies by deterring shipowners and regional producers from using the vital waterway.
The escalation marks a sharp reversal from earlier expectations of a supply glut, after OPEC+ increased production quotas and Middle Eastern producers moved to ramp up output.