Two Iranian fast boats approached the U.S. Wasp-class amphibious assault ship Essex on Friday while it was operating in the Persian Gulf, according to U.S. defense officials.

The commander of U.S. Central Command, Gen. Joseph Votel, was on board the Essex at the time of the incident, officials have confirmed.

“Today’s interaction with U.S. 5th Fleet forces and the IRGCN [Islamic Revolutionary Guard Corps Navy] was characterized as safe and professional," U.S. Naval Forces Central Command told Marine Corps Times in an emailed statement. “The U.S. Navy continues to operate wherever international law allows.”

The IRGCN has a history of harassing U.S. warships in the Persian Gulf — an activity some analysts have noted recently has decreased.

The Wall Street Journal has reported that since Jan. 2016 there had been an average of more than two “unprofessional” encounters a month between Iranian fast boats and U.S. warships, for a total of nearly 50 incidents over a two-year period.

But the last “unprofessional” encounter occurred on Aug. 14, 2017, NAVCENT told Marine Corps Times.

During that incident, an Iranian drone operating without any navigational lights flew near U.S. aircraft conducting night operations aboard the U.S. aircraft carrier Nimitz.

Marines with 13th Marine Expeditionary Unit are currently embarked on the Essex. The Essex also is hauling Marine Corps F-35Bs.

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The presence of the F-35s is a first for the U.S. Central Command area of operations.

CNN was first to report the encounter between the Iranian fast boats and the Essex.