Well, we could start at sea by announcing our withdrawal from the treaties which forbid the granting of letters of marque and reprisal, and Congress could authorize the outfitting of privateers to harry the shipping of enemy nations.
I was thinking just yesterday that, in a time of asymmetric warfare, that we should go back to assasination and intel head games. If the other side wants to fight dirty, we get dirtier. And we have the toys to do just that - UAVs with Hellfires. Increase the pucker factor tenfold for the tyrants.