Iran war live: Trump claims US Navy blockade stops Iranian ships in Hormuz

JUST IN: Trump says the US Navy has blockaded the Strait of Hormuz, claiming all Iranian ships have been stopped from crossing.

President Trump says the US Navy has blockaded the Strait of Hormuz, and that every Iranian ship has been stopped from crossing.

He's calling the blockade effective, and that word is doing a lot of work. Here he is making the claim, and so far it's his claim alone, with no independent confirmation of how many ships have been stopped or where. The strait handles roughly a fifth of the world's oil, so even the announcement moves things. Commercial shipping, vessels like this one, now has to price in a US naval cordon at the planet's most important chokepoint.

And the war is widening beyond the strait. The UK Foreign Office is now advising against all but essential travel to Saudi Arabia, after attacks on the kingdom by Yemen's Houthis.

A blockade is historically treated as an act of war. That's the line the United States just said it crossed.

This is Angel Manalo, reporting for HIT.