American support for Ba'athist Iraq during the Iran–Iraq War, in which it fought against post-revolutionary Iran, included several billion dollars' worth of economic aid, the sale of dual-use technology, non-U.S. origin weaponry, military intelligence, and special operations training. However, the U.S. did not directly supply arms to Iraq. Of particular interest for contemporary Iran–United States relations are the repeated accusations that the U.S. government actively encouraged Iraqi leader Saddam Hussein to invade Iran (proponents of this theory frequently describe the U.S. as having given Saddam a green-light), supported by a considerable amount of circumstantial evidence, but the U.S. government officially denies that any such collusion occurred, and no conclusive proof of it has been found.