(Bloomberg) -- The U.S. military is warning that Iranian naval forces may increase “aggressive actions” against American and allied commercial ships, citing reports from crews that experienced navigation and communications jamming.
“Vessels have reported GPS interference, bridge-to-bridge communications spoofing, and/or other communications jamming with little to no warning,” U.S. Central Command said in a statement Thursday that suggested Iranian forces may be attempting to steer ships into its waters to provoke a confrontation.
The warning was delivered in a statement that also cited an advisory late Wednesday from the Transportation Department’s Maritime Administration. It set out procedures consistent with a new joint effort by the U.S. and U.K. to protect shipping in the Persian Gulf and the Strait of Hormuz, a chokepoint for oil shipping in the region.
The advisory said crews of U.S.-flagged ships should notify both the U.S. and the U.K. when transiting the region.
If Iranian forces attempt to board U.S.-flag vessels, the Maritime Administration said, the crew should identify the ship, “affirm that they are proceeding in according with international law” and “immediately inform the U.S. Fifth Fleet Battle Watch.”
If Iranians demand to board, the agency added, “the ship’s Master should, if the safety of the ship and crew would not be compromised, decline permission.”
The U.K. announced on Monday that it’s “spearheading” an international mission to protect shipping in the Gulf, working with the U.S.
Other nations have balked at joining a U.S.-led effort because they blame President Donald Trump for inflaming tensions when he quit the 2015 multinational accord that eased economic sanctions on Iran in return for curbs on its nuclear program.