Dubai: The US Navy warned on May 19 it will take “lawful defensive measures” against vessels in the West Asia that come within 100 meters (yards) of its warships, offering specific guidelines after a recent close encounter with Iranian vessels in the Persian Gulf.

Defensive measures have typically included turning a ship away from the approaching vessel, sounding its horn, shooting off flares and ultimately firing warning shots to force the vessel away. But offering a specific distance is new for the Navy.

“Our ships are conducting routine operations in international waters wherever international law allows and do not seek conflict,” said Cmdr. Rebecca Rebarich, a Bahrain-based 5th Fleet spokeswoman. “However, our commanding officers retain the right to self-defence if deemed necessary.”

Iran’s paramilitary Revolutionary Guard acknowledged on May 17 it had a tense encounter with US warships in the Persian Gulf last week, but alleged without offering evidence that American forces sparked the incident.

The US Navy has years of experience with Iranian forces getting that close, namely the hard-line, paramilitary Revolutionary Guard. Their armed speedboats routinely cut across their paths when going through the Strait of Hormuz, the narrow mouth of the Persian Gulf through which 20 per cent of all oil passes.

Tensions have been high between Iran and the US ever since President Donald Trump unilaterally withdrew America from Tehran’s nuclear deal with world powers in 2018.

Last summer saw a series of escalating attacks targeting oil tankers and other sites around the Persian Gulf. It reached a crescendo in January with the US drone strike in Baghdad that killed Iranian Gen. Qassem Soleimani and an Iranian ballistic missile strike of American forces in Iraq in retaliation.

In April, Trump warned on Twitter: “I have instructed the United States Navy to shoot down and destroy any and all Iranian gunboats if they harass our ships at sea.”