Sorry but that scenario is nonsense. If President Trump decides to use force it will be overwhelming force. Not a single tomahawk so he can sit back and see what Rocket Man does in response.
Agreed, NK has too much power to take out SK. They are all offensive. NK needs to be neutralized in one single fast attack. Then as the dust settles, anything that moves needs to be blown up. There is no reason to allow NK to have time to react. If they see it coming they will try to fire what they have at SK.