You have to use common sense.  If countries felt the US would not use force to stop them from gaining nuclear weapons.  WHat would make them fear going for them.  Look at Iran has the UN done anything NO!  The only thing they fear is our military right now we are tied up in Iraq so they are betting we wont attack because we dont have the forces.  Deploymacy should be first option but if it doenst work at 3 plus years like it isnt with IRan  force is needed and that is the BEST deterant.