In fact a little demo might be in order. We and our close allies are the only countries that have actually stopped testing nuclear weapons. Everyone else does what they think they can ge away with and just denies it. The intellegence community in every country knows the truth but the public denials keep the political harm to near zero.
In that spirit, let's set off a tactical nuke of say 500 tons in Afaganistan at a barren spot that we control. Everyone will know what it was, but we will deny it. Call it a minor earthquake or something. It will send the right message.