PERSIAN GULF — Iranian Navy fast boats came close to the USS Essex, a U.S. Navy assault ship, and at least one of the other ships in the Essex Amphibious Ready Group in the Persian Gulf Friday while a top U.S. general was aboard.
The armed Iranian Revolutionary Guard Corps Navy FIACs (fast inshore attack craft) approached both the USS Rushmore and the Essex, coming within about 300 yards of the Essex at one point.
NBC News was on the ship's bridge during part of the incident.
Gen. Joseph Votel, commanding general of U.S. Central Command, was visiting and watching from the bridge as six Iranian FIACs moved closer to the Essex and as one cut straight in front of the ship's path.
"What is the prefix of your side number?" an Iranian sailor asked over a radio transmission, another way of asking the Essex its nation of origin. An American sailor on board the Essex identified the U.S. ships to the Iranians, describing them as coalition warships. The Iranian boats continued to maneuver around the U.S. ships, even after the Essex warned of danger.
The captain of the Essex described the interactions as "safe and professional," but said they were "annoying."
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Capt. Brian Mutty said that during a radio transmission from earlier in the day an IRGCN sailor issued a threat, warning that if the Essex continued to fly one of its helicopters around the Iranian boats, the Iranians would shoot at it.
The chopper continued to fly, no shots were fired and the U.S. ships were not forced to deviate from their course during the interactions.
Gen. Votel called the interactions "normal, safe and professional interaction out here in international waters." He went on to praise the professionalism and vigilance of the Essex crew.
Votel described the Iranian boats' behavior as normal, and said much of what the Iranians do in the region is "shadowing."
"They are trying to watch what we're doing and trying to characterize it," he said during an interview on the USS Essex.
From about 7:00 a.m. to 9:30 a.m. local time, two Iranian Cougar class boats and two Kuch-class boats shadowed the Essex, coming within 700 yards.
At 9:30 a.m., two Iranian Peykapp-class patrol boats arrived and the other four craft left. One of the two Peykapp boats came within 300 yards of the Essex.
Over the summer, President Trump tweeted that the Iranian Navy had not harassed any U.S. Navy ships in the region during all of 2018.
While the U.S. Navy hasn't had any interactions with Iran that the U.S. deemed unsafe and unprofessional or as full-fledged "harassment," Iranian boats in the region continue to pester ships on a routine basis, according to the sailors on board the USS Essex.
Capt. Gerald Olin, commander of the Amphibious Ready Group, said Iranian boats shadowing U.S. Navy ships was still routine while operating in the region, especially in international waters.
He described another radio transmission with the Iranians, explaining that the Iranians, "questioned what we were doing." He said it is common for Iranian boats to approach U.S. ships maneuvering to within a quarter of a mile.
Asked whether the re-imposition of sanctions against Iran in early November could lead to more aggressive actions by Iran in the area, Gen. Votel said, "I think Iran is always a concern," adding, "we will be vigilant as we always are."
Courtney Kube is a correspondent covering national security and the military for the NBC News Investigative Unit.