Iran's Revolutionary Guard navy has warned of a “heavy assault” on one of the U.S. bases in the region if Iranian oil tankers or commercial vessels are attacked. Iranian state TV reported the warning a day after the U.S. struck two Iranian oil tankers. Meanwhile, Bahrain says it has arrested dozens linked to Iran’s Revolutionary Guard. The Persian Gulf country hosts the U.S. Navy’s regional headquarters. Britain is deploying a warship to the Middle East to protect commercial ships in the Strait...