Trump said his administration had contacted seven countries asking for support to allow shipping through the vital waterway

Japan and Australia said they have no plans to send ships to help secure the strait of Hormuz, the vital waterway that Iran has mostly blocked to oil tanker traffic, as Donald Trump ramps up pressure on allies to provide support.

The effective closure of the strait of Hormuz by Tehran, in retaliation for airstrikes by the US and Israel, has proved catastrophic for global energy and trade flows, causing the largest oil supply disruption in history and soaring global oil prices.

Trump on Sunday said his administration had already contacted seven countries for support, but declined to identify them. In an earlier social media post, he said that he hoped China, France, Japan, South Korea, Britain and others would participate.

“I’m demanding that these countries come in and protect their own territory because it is their territory,” Trump told reporters aboard Air Force One on the way from Florida to Washington on Sunday. “It’s the place from which they get their energy.”