[jjk166]

The Non-Proliferation Treaty actually does bar non-weapons state signatories from developing nuclear weapons themselves, and requires them to accept IAEA safeguards to ensure they are not doing so. The issue with North Korea is that they withdrew from the NPT, then re-entered it, then when they tried to withdraw again they did not give the 3 months notice required by the treaty. They claim that their re-entry into the treaty was merely a delay in their withdrawal, and thus they didn't need to give notice again. The rest of the world disagrees, and holds they are in violation of the treaty, and has sanctioned them accordingly. Sanctions are generally the worst punishment that violating a treaty can result in, barring the few exceptions where war would be both justified and practical.