Chemical Reaction: The U.S. presses Libya over a nerve-gas plant

The unlikely combination of Ronald Reagan and Muammar Gaddafi resembles nitroglycerin: it can produce an explosion at the slightest jolt. Last week, for the fourth time since 1981, just such a blowup took place in the Mediterranean skies off Tobruk, where a shootout that could have been taken right from the movie Top Gun ended in the downing of two Libyan jets by American pilots.

This time, however, there was a major difference. While the first three incidents occurred when Washington decided to swat the desert dictator, the latest confrontation was wholly unexpected. When the Libyan MiGs were destroyed after they...