Global Thermonuclear War on another planet

Current radio searches for extraterrestrial intelligence (SETI) look for intelligent-looking radio signals. But what is the brightest signal an intelligent species can produce? For us, it is probably an atomic or hydrogen bomb. Inspired by Battlestar Galactica, is it possible to search the skies for a nuclear detonation? Or is it too similar to stellar fusion? Surely every day somewhere in the universe some species must be busy exterminating itself in global nuclear armageddon.