CAIRO, Egypt - The U.S. navy says one of its ships fired warning shots at a small Iranian boat in the Persian Gulf in December during one of two serious encounters that month.

A navy official says the USS Whidbey Island fired the shots on December 19th in response to a small Iranian boat that was rapidly approaching it.

The official says the smaller boat stopped after the U.S. ship fired.

It's the first official confirmation that the United States had fired warning shots in any recent confrontation with Iran in the Gulf.