The U.S. Navy said its actions were "safe and professional” in an incident in the Gulf that led to a U.S. helicopter firing warning flares at a vessel operated by Iran’s Islamic Revolutionary Guards Corps (IRGC).
The Navy on July 29 said one of its helicopters was on patrol in international airspace when it spotted several rocket-bearing Iranian vessels approaching U.S. ships "at a high rate of speed."
The helicopter attempted to establish communications with the vessels but did not receive a response, leading it to send out warning flares, officials with the Bahrain-based U.S. 5th Fleet said.
The firing of the flares led the Iranian ships to cease their approach, the Navy said.
The Navy said the helicopter was attached to the USS Nimitz supercarrier and an accompanying warship.
Iran's IRGC said its vessels were near the Resalat oil and gas platform when the incident occurred.
"The Americans made a provocative and unprofessional move by issuing a warning and shooting flares at vessels...” its statement said.
The incident comes after a U.S. Navy patrol craft on July 25 fired warning shots near an Iranian vessel that U.S. sailors said came within 150 yards (137 meters) of them.
The Navy said the Iranian vessel ignored radio calls, flares, and the ship's whistle.
During the presidential campaign, now-President Donald Trump warned that any Iranian vessels that harassed U.S. craft in Gulf would be "shot out of the water."
Since taking office, his administration has assumed a hard line on Iran, recently warning that the country was not following the spirit of a 2015 nuclear agreement with the United States and other world powers in which Iran limited its nuclear activities in exchange for sanctions relief.
On July 28, the U.S. Treasury Department imposed sanctions on six subsidiaries of an Iranian company that it said was "central" to Tehran's ballistic-missile program.
The Treasury said the sanctions were in response to Iran’s “continued provocative actions,” including the July 27 launch of a satellite-carrying rocket.
U.S. and other Western officials have said the technology used in the launch of the rocket could be converted to carry nuclear warheads and, therefore, violated the 2015 accord.