You've Got A Dozen, We've Got 5113 (plus tens of thousands more)

http://www.cnn.com/2010/POLITICS/05/03/us.nuclear.warhead.count/index.html?hpt=T3

Most of those inactive warheads can be restored, at a considerable cost, within a year, if desired. Say 10,000 more, if re-engineered to modern specs. Most would be two-stage weapons (200 KT or less), with less maintenance.

Some 100-200 or so would be 1 MT+ weapons, with much improved designs. EMP weapons would almost certainly be part of that stock. Add on the EC (greater than 10 MT) weapons for shock value, about fifty, or so. Those would be air-delivered.

This would be done, regardless of political party in power, if the US felt threatened.

This alone will cushion the loss-of-empire. No other nation in history (not even the Russians) has had this kind of capability. US prestige, currency, and standards of living may drop, but we have the spade royal flush (including S%W for backup). This is a deliberate show of cards to the other players, particularly the Chinese. Loosen up the currency, Beijing.