Iranian small boat threats, limpet mines and Tehran-backed forces armed with cruise and anti-ship killing missiles are just a few of the threats to the shipping channel in the Persian Gulf that supplies nearly one-fifth of the world’s global crude oil. To bolster the security of US warships at sea operating in tight waterways around the Middle East, the U.S. conducted an exercise in December using Griffin missiles fired from the U.S. Cyclone-class ship Hurricane.