On July 3, 1988, the USS Vincennes shot down Iran Air 655, an airliner traveling from Bandar Abbas to Dubai. The USS Vincennes, which had earlier been harassed by Iranian small boats, believed they were under attack and crewmen misinterpreted the data as the Iranian airliner approached. (Iran for its part had failed to warn the civilian airliner to avoid the sector in the Persian Gulf where the Vincennes was operating, as was standard when skirmishes had occurred).
It was a tragic mistake, and one for which the United States subsequently apologized. What was less known, however, was the impact the downing had on then-Supreme Leader Ayatollah Ruhollah Khomeini. When Iraq attacked Iran in 1980, Khomeini ordered all Iranians to defend their country. The Iran-Iraq War was like World War I on steroids, with trench warfare, machine gun nests, minefields, and mustard gas--and SCUD missiles flying back and forth. By 1982, the numerically superior Iranian forces had more or less pushed back their Iraqi counterparts. Declassified Iranian documents show that Khomeini was considering a ceasefire then, but the Islamic Revolutionary Guard Corps interceded and convinced the Iranian leader to continue to fight so that they might try not only to rid Iraq of Saddam Hussein, but also continue on the warpath to eradicate Israel. There followed six more years of stalemate and perhaps a half-million more casualties. Then came the shootdown of Iran Air 655. Khomeini’s conspiracy-addled mind could never accept that its downing was an accident, but he recognized its impact on the Iranian public. He also concluded that if the United States was willing to go so far as to shoot down an airliner, Washington would stop at nothing to prevent Iran from achieving its war aims. He decided then to accept the ceasefire, likening it to drinking from “a chalice of poison.”