Our conventional weapons and economic influence are the leverage and deterrents. It's pretty unlikely that we would ever again nuke a non-nuclear entity. The non nuclear entities know this, so nukes don't really provide any leverage over them. It's our drones, ships, etc. that do, at least on the military side.

For the few entities with nuclear weapons, it's MAD. We would only play the card once, since it would be the final round of the game with that entity.