The U.S. plans to send 1,500 troops and other military assets to the Middle East to counter the Iranian threat. Those who worry about the possibility of war ignore that Iran is already at war and has been for almost 40 years. Its recent sabotage of commercial vessels in the United Arab Emirates and pipelines in Saudi Arabia continues a long pattern that began with the invasion of the U.S. Embassy in Tehran in November 1979.

Iran established Hezbollah in Lebanon in the early 1980s. In April 1983, Hezbollah attacked the U.S....