Should the Nuclear Non-Proliferation Treaty be enforced on all nations?

If Iran (which is a signer) agrees to comply, should North Korea (which violated it and withdrew) be forced to comply. Also, should non-signers: India, Pakistan and Israel be admitted as Nuclear Weapons states (which they are), subject to IAEC inspections and should the US stop sharing weapons with NATO? Should an automatic, absolute international trade embargo be imposed on all violators?