Story highlights More incidents with Iran this year than all of last year

US officials say Iran flexing its muscles in the Persian Gulf

(CNN) Seven Iranian fast-attack boats were involved in an unsafe encounter with the USS Firebolt over the weekend, with one Iranian craft coming to a stop in front of the American ship, a US defense official told CNN Tuesday.

The provocative maneuver, which on Sunday brought the Iranian boat within 100 yards of the Firebolt, a coastal patrol boat that carries a crew of about 30, was assessed by the US to be unsafe and unprofessional and could have led to a collision, the official said.

There have been 31 unsafe America encounters with Iranian vessels in the Persian Gulf so far this year, up from 23 in all of 2015, the official said.

Less than two weeks ago, US naval ships in the northern Persian Gulf were harassed by an Iranian Revolutionary Guard Corps vessel, which came within 200 yards of the US ships. Following standard maritime procedures, the USS Squall fired three warning shots to ensure the Iranians understood they needed to leave the immediate area.

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