Ronald Reagan was fond of quoting John Adams, who famously said: “Facts are stubborn things.” So when Iranian Foreign Minister Javad Zarif made public pronouncements about fighting extremism, the facts show that his comments are ironic at best and little more than insincere propaganda.

The fact is that Iran is the leading state-sponsor of terrorism, with government officials directly responsible for numerous terrorist attacks since 1979. These include suicide bombings of the U.S. Embassy in Beirut and the Marine barracks at...