The Pentagon is accusing Iran of "unsafe and unprofessional" conduct after a naval helicopter flew within about 25 yards of a U.S. Navy ship and circled it three times in the Gulf of Oman.

Pentagon press secretary John Kirby on Monday said the Iranian helicopter circled the USS Essex, an amphibious assault ship, three times and at one point flew as low as 10 feet off the surface of the water. He said the incident on Nov. 11 had no effect on the Essex’s operations.

"Without getting into specifics, the crew of the Essex took the appropriate force protection measures they felt that they needed to, and they acted in accordance with international law," Kirby said.

"This one ended peacefully, but it doesn't mean it was safe and professional. It absolutely wasn't," Kirby said. "And, again, our commanders have the right of self-defense; they have to make those calls in the moment. There are rules of engagement that help guide them."

Video emerged over the weekend in Iranian media of the helicopter appearing to fly close to the Essex, CBS News reported.  

It’s not the first time Iranian forces have been called out for "unsafe and unprofessional" encounters with U.S. vessels.

In May, the Navy criticized the Iranian Islamic Revolutionary Guard Corps navy, a branch of the Iranian armed forces, after a fast in-shore attack craft conducted maneuvers while near U.S. naval vessels that were in the Strait of Hormuz, The Hill reported.

The new encounter comes days after Iran said its military warned off U.S. RQ-4 and MQ-9 drones that approached during its annual war games exercises, the news outlet noted.

The Associated Press contributed to this report.

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