Of course. But you don't need missiles or aircraft to deliver a nuke.

A gun-type weapon assembled in place in a city, criticality achieved by a suicide, could yield about .8 KT (the equivalent of 1,600,000 pounds -- or 72,574.7792 kilograms -- of TNT) and a whole lot of radiation and radioactive "dirt". Or place a nuke artillery shell in the hold of a tanker, under the oil.

And I can think of even worse things which I won't go into here.