U.S. oil prices climbed above $75 a barrel after President Donald Trump said Washington would reinstate a blockade on Iranian ships and impose a toll on cargo passing through the Strait of Hormuz, according to CNBC. The move came as the U.S. and Iran traded strikes over the weekend and disputed whether the strategic waterway remained open to ship traffic.

Trump said the strait will remain open “with or without” Iran and that a 20% rate would be charged on all cargo shipped through it, the Guardian reported. The BBC also reported that Washington will charge a 20% toll on all cargo moving through the Strait of Hormuz, alongside the reinstated naval blockade of Iranian ports.

The announcement followed a fresh wave of U.S. attacks on Iran. Tehran said diplomacy had proven “futile,” according to the Guardian, and stated it had struck U.S. military facilities and infrastructure in the region.

Bahrain’s military accused Iran of targeting civilians in its latest attacks on the kingdom. “Iran continues its systematic hostile approach through its heinous attacks with missiles and drones that target civilians in the Kingdom of Bahrain,” the general command of Bahrain’s military said, adding that its air defences “intercepted and destroyed a number of Iranian aerial attacks” that morning.

The dispute over whether Hormuz is open to traffic sits at the center of the market reaction. The U.S. and Iran disagreed over the status of the waterway after the weekend’s exchange of strikes, according to CNBC, leaving traders and shippers facing uncertainty over one of the world’s most important energy chokepoints.