A U.S. Navy video and several photos show Iranian vessels harassing U.S. Coast Guard ships in the Persian Gulf earlier this month, the first such incident in almost a year.

Three Iranian Islamic Revolutionary Guard Corps Navy (IRGCN) fast-attack boats and one larger support vessel, Harth 55, swarmed U.S. Coast Guard patrol boats Wrangell and Monomoy during maritime security operations in international waters on April 2.

The U.S. Navy says that during the three-hour incident, the Harth 55 “repeatedly crossed the bows of the U.S. vessels at an unnecessarily close range,” at one point coming within 70 yards of the U.S. ships.

One “unsafe and unprofessional” approach, as the Navy described it, was captured on video.

The U.S. Navy said the large Iranian vessel “closed aggressively” with the Wrangell, forcing it to maneuver to avoid a collision while blowing the horn.

In addition to blasting the horn five times, the U.S. ships also radioed the Iranian vessel. The Harth 55 responded to bridge-to-bridge communications but did not alter its behavior. The IRGCN vessels eventually withdrew after about three hours.

The Navy said that “the IRGCN’s actions were deemed unsafe and unprofessional” because “their actions increased the risk of miscalculation and collision.”

The two Coast Guard vessels are assigned to Patrol Forces Southwest Asia and operate under U.S. Naval Forces Central Command’s Task Force 55.