France Nukes the USA

[xoxoxoBruce]

sproglet posted

A lot of people make the mistake of underestimating the French.
They've got big bombs, the Foreign Legion and enough arrogance to use both.

This got me wondering, if France nuked an American target, even by accident, what would we do? What could we do?
Nuking France puts a lot of other countries in serious danger. Especially Briton, Spain/Portugal and the Low Countries, down wind from France.

What would Bush do?
What would a normal person do in his place?