President Donald Trump got a great 80th birthday present from Iran ... an alleged end to fighting in the region -- and the reopening of the Strait of Hormuz.

POTUS announced the deal between the USA and Iran on Truth Social just moments ago ... congratulating all sides on getting it done.

DJT says he's authorizing the full and unconditional reopening of the Strait of Hormuz ... while also ending the U.S. naval blockade in the region.

He adds, "Ships of the world, start your engines. Let the oil flow!

As you know ... Iran quickly shut down the strait after the United States and Israel attacked the country back in February -- killing Supreme Leader Ali Khamenei in the process.

The two sides have exchanged barbs for months ... and progress toward a deal has been slow -- despite Vice President J.D. Vance's past trip to Pakistan.

Just days ago, Trump ordered a retaliatory strike against Iran after the country took down a U.S. Army Apache helicopter ... and a peace agreement seemed further away than ever.

It's unclear what more the two sides need to do in order to codify the agreement ... but, if President Trump's right, peace is within sight.