WASHINGTON — A group of Iranian vessels from the country's Revolutionary Guard Corps harassed two U.S. Coast Guard ships over three hours in the Persian Gulf earlier this month, repeatedly crossing in front of the bows of the American ships at close range, the U.S. Navy said Tuesday,
It was the first such incident in a year and the encounter on April 2 came just as the U.S. and Iran had committed to starting negotiations on reviving the 2015 nuclear agreement between Tehran and world powers.
Three Iranian fast-attack boats and one larger ship, a 180-foot, twin-hulled vessel called the Harth 55, approached and swarmed the Coast Guard ships at close distances. The larger Iranian ship repeatedly crossed in front of the two Coast Guard vessels "at an unnecessarily close range," coming within 70 yards, according to a statement from the Navy's Fifth Fleet in Bahrain.
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"The U.S. crews issued multiple warnings via bridge-to-bridge radio, five short blasts from the ships' horns, and while the Harth 55 responded to the bridge-to-bridge radio queries, they continued the unsafe maneuvers," the Navy said.
The two Coast Guard ships, the Monomoy and the Wrangell, carried out defensive maneuvers to avoid a collision during the three-hour encounter, the Navy said.
The Iranian vessels' maneuvers were "unsafe and unprofessional" and "increased the risk of miscalculation and collision," the Navy said. The Iranians' actions violated international law and internationally-recognized maritime customs, it said.
Iran's U.N. mission did not immediately respond to a request for comment.
The Wall Street Journal first reported the incident.
Fast-attack craft from the Revolutionary Guard Corps have swarmed and shadowed U.S. warships over the years but the activity dropped off starting in 2018.
It was unclear why the U.S. military did not share details about the April 2 incident until now.
Pentagon press secretary John Kirby told reporters he was not aware of any policy discouraging the U.S. military from divulging information about encounters with Iranian forces to avoid derailing diplomatic efforts.
"There's no pressure from anyone in the administration to meter up or meter down communications activities regarding these sorts of incidents," Kirby said.
He added: "We obviously don't want to see miscalculation and these kind of events could spiral into miscalculation and that's not good for anyone in the region."
Some regional experts say the Revolutionary Guards has sought to provoke tense encounters in the past to undermine President Hassan Rouhani's diplomacy with the West.
In a leaked audio recording posted over the weekend, Iranian Foreign Minister Mohammad Javad Zarif can be heard saying that the Revolutionary Guards have often undercut the government's diplomacy and that he had "zero" influence over foreign policy.
"I have never been able to tell a military commander to do something in order to aid diplomacy," Zarif said, according to the recording, which was aired by the London-based Iran International Persian-language satellite news channel on Sunday.
Iran's foreign ministry did not dispute the recording's authenticity, but it said the news outlet only published excerpts of the seven-hour interview with Zarif and that the comments and that the comments were taken out of context.