The two ships were just a few hundred yards apart on July 25 when Iranian crewmembers pointed what are believed to be on-deck machine guns at the warship and the U.S. military helicopter that had just landed on that coalition ship's deck, the Defense official said.
However, the coalition warship and helicopter crew quickly noticed there was a cameraman standing right behind one of the Iranian gunners.
"Were they just trying to get cool pictures pointing at us? Were they making a propaganda film? Was some guy taking pictures to send to his girlfriend? We don't know," the Defense official said.
The entire incident lasted about a minute with no shots being fired and no action taken by the coalition warship. The U.S. helicopter stuck to its plan as well and left the deck on schedule, the official said. The official declined to identify the nationality of the coalition warship but said the Iranian warship was a regular Iranian Navy Vosper-class frigate.
In a statement released early Wednesday afternoon, the U.S. Navy characterized the interaction as "unsafe and unprofessional."
The U.S. Navy took photos of the incident but has not publicly released them. The incident was observed by the USS Farragut, which had launched the U.S. helicopter.
The official said it's been several weeks since there have been any serious encounters with Iranian military ships, although on two recent occasions, U.S. Navy ships did sound their horns to warn Iranian ships they were too close, and those ships moved to a farther distance.
The U.S. Navy said its forces are routinely approached by Iranian warships as they operate in the region, with the majority of all interactions by the Iranians conducted "in a safe and professional manner."