US accuses Iran navy of 'dangerous' harassment in Gulf
The Pentagon said the Iranian Revolutionary Guard Corps (IRGC) boats "repeatedly crossed the bows and sterns of the US vessels at extremely close range and high speeds", coming at one point within 10 yards (nine metres) of the bow of one.
At the time the American ships were conducting operations in international waters in the northern Gulf with Apache attack helicopters and were forced to change course, the US navy said in a statement.
The much smaller speedboat-like IRGC navy vessels ignored warnings from the US ships for about one hour, before finally responding to radio communications and then leaving, the US said.
"The IRGCN's dangerous and provocative actions increased the risk of miscalculation and collision," the US said, adding they violated maritime customs and laws.
The US Naval Institute released footage of the incident, showing Iranian soldiers with guns mounted on speed boats, circling the American vessels.
The past year has been marked by escalating tensions between the US and Iran, stoked by a spate of still unexplained attacks on shipping in and around the Gulf involving Iran and Western powers. There have also been devastating drone attacks on Saudi oil installations.
Washington accused Tehran of attacking the vessels with mines and drones, something it has strongly denied.
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