For example he could set off a single low-yield high-altitude explosion to demonstrate that he "means business". And watch with delicious expectation as the Western world shits its pants.
It is unfortunately a comparatively low-risk, but sickeningly attractive proposition for him to consider -- especially if he finds himself backed into a corner with his own survival threatened (as will be the case if the war reaches a point where he is seen to be intractably failing).
