The Cold War era had a certain logic -- that once the US and USSR were effectively destroyed -- allies and neutral countries, even non-nuclear ones -- would bec

The Cold War era had a certain logic -- that once the US and USSR were effectively destroyed -- allies and neutral countries, even non-nuclear ones -- would become threats. If any missiles remained unfired, might as well re-target. In other words, destroying the USSR only to be conquered by Mexico would have provided an ironic epitaph for the USA.