A U.S. Navy ship had to change course to avoid colliding with an Islamic Revolutionary Guards Corps attack boat that came within 100 yards of it in the Persian Gulf, Pentagon officials said on September 6.
The incident on September 4 was the fourth such encounter in a month. U.S. officials say they are concerned such incidents could lead to mistakes.
Pentagon spokesman Captain Jeff Davis said the Iranian fast-attack vessel sailed directly in front of the USS Firebolt and stopped, forcing it to veer off course. The incident began when seven Iranian ships "harassed" the Firebolt, he said.
Davis called the Iranian maneuvers "unsafe and unprofessional" and said that uncovered and manned weapons were seen on the Iranian vessel.
The U.S. ship tried to communicate with the Iranian ship by radio three times but received no response.
The Pentagon said there have been 31 similar interactions with Iranian ships this year, almost double the amount from the same period last year, and more numerous than incidents recorded with any other nation.
"This is clearly a pattern, and it's one we're not happy about, and we'd like to see this sort of behavior stop," Davis said.