Iraq invaded Iran in 1980, not 1987. Well before Ronnie Raygun got into the White House.
As for the US (and almost everybody else's support for Iraq at the time), the rule My Enemies Enemy is My Friend comes into play , unless you would like just to make a profit in the case of the Exocets and Mirage F1's/loaned SuE's that ended up in Iraq. In the US's case, when you storm my embasey and hold its staff hostage, that is usually counted as a act of war. The best line I heard about that war was from a USAF general....'Its a pity that both sides in that war can't lose'