Tensions are mounting in the Persian Gulf, with U.S. naval vessels firing two rounds of warning shots at boats belonging to the Iranian Revolutionary Guard. April saw the first such encounter in four years, a rapid increase in the rate of conflict as officials meet in Vienna to discuss reinstating Iran’s nuclear treaty.

Monday’s encounter was precipitated by 13 Iranian vessels that encroached on a set of six U.S. warships escorting the USS Georgie, a guided missile submarine, through the Strait of Hormuz.

Warning volleys were fired from a 0.50-caliber machine gun, once when the boats got within 300 yards and again at 150. After the second volley, the Iranian vessels retreated.

“They were acting very aggressively,” Pentagon press secretary John Kirby told reporters. “Sadly, harassment by the IRGC Navy is not a new phenomenon. It is something that all of our commanding officers and the crews of our vessels are trained to for.”

It’s the second time in less than a month that the Navy has been forced to fire warning shots. The last incident, on April 26, was the first of its kind in over four years.

“This activity is the kind of activity that could lead to somebody getting hurt and could lead to a real miscalculation there in the region, and that doesn’t serve anybody’s interests.”

The conflict comes as negotiators from the U.K., China, France, Germany, Russia and Iran meet in Vienna with the hope of coming to an accord on Iran’s nuclear program.

Former U.S. President Donald Trump crippled the original agreement, but diplomats have noted a “new energy” to see it restored.

The Biden administration has signaled it would like to reenter into the deal.

An earlier incident in which an Iranian navy ship crossed the bow of a US patrol boat in the Gulf on April 2, 2021 An earlier incident in which an Iranian navy ship crossed the bow of a US patrol boat in the Gulf on April 2, 2021 Photo: US NAVY / -