US Senator Tom Cotton speaks to the media after attending a briefing with administration officials about the situation with Iran on January 8 in Washington, DC. Photo: AFP

Eleven vessels from Iran's Islamic Revolutionary Guard Corps Navy (IRGCN) came dangerously close to US Navy and Coast Guard ships in the Gulf, the US military said on Wednesday.

While such interactions had occurred occasionally a few years ago, they had stopped, and this incident comes at a time of increased tensions between the two countries.

According to the statement, the Iranian vessels approached six US military ships while they were conducting integration operations with Army helicopters in international waters.

At one point, the Iranian vessels came within 10 yards of the US Coast Guard cutter Maui.

The US ships issued several warnings through bridge-to-bridge radio, blasts from the ships' horns and long-range acoustic noise making devices. 

The Iranian ships left after about an hour, the statement added.

Iran's Islamic Republic News Agency (IRNA) issued a brief Farsi-language story on the US military report, without any reaction from Iranian authorities.

"The IRGCN's dangerous and provocative actions increased the risk of miscalculation and collision, [and] were not in accordance with the internationally recognized Convention on the International Regulations for Preventing Collisions at Sea," the statement said.

Secretary of State Mike Pompeo was asked in a Fox News interview whether he had discussed the incident with the Pentagon, saying: "We've talked as a team. ... We're evaluating how best to respond and how best to communicate our displeasure with what ... took place."

Reuters