CNN - Barbara Starr

At a time of heightened tensions with Iran, U.S. military officials confirm to CNN that on January 6, U.S. military and Coast Guard ships had two close encounters with high-speed Iranian boats in the Strait of Hormuz and Persian Gulf that exhibited provocative behavior.

A senior U.S. military official confirms the following to CNN:

The USS New Orleans, an amphibious transport ship was sailing through the Strait of Hormuz into the Persian Gulf when three Iranian Navy speed boats rapidly approached within 500 yards of the ship. The Iranians did not respond to whistle signals or voice queries from the New Orleans. The lack of response disregards standard maritime protocols. The boats eventually broke away.

On the same day the U.S. Coast Guard cutter Adak was also harassed by high-speed Iranian Navy boats while operating 75 miles east of Kuwait City. Iranian personnel in the small boats appeared to be holding AK-47 rifles and at least one video camera. U.S. personnel on the cutter also report seeing a forward gun that was manned on one of the Iranian boats. Eventually, communications with a larger Iranian vessel in the area were established and the speed boats stopped their harassment.

While the U.S. Navy has had regular routine encounters with Iranian naval forces for years, the Navy has reported in recent weeks seeing more aggressive action from Iranian-flagged vessels which it believes carries the potential for miscalculation. Typically Iranian small boats are operated by forces of the Iranian Revolutionary Guard Corps force and are considered to be more aggressive than regular Iranian forces. No shots were fired in either incident.

Both incidents were videotaped and the Pentagon may release that video later Friday.

Word of the aggressive encounters by Iran comes as the US in recent weeks has twice rescued Iranian mariners at sea—one time a crew captured by pirates and another when a ship had mechanical problems.