The global nuclear non-proliferation regime, as it has evolved since the entry into force of the Nuclear Non-Proliferation Treaty (NPT) in 1970, has been remarkably resilient. Despite predictions of a “cascade of proliferation,” there are currently only nine states with nuclear weapons, and that number has remained the same for the past 25 years.1 The NPT is nearly universal, with 190 parties and only five non-parties (India, Israel, North Korea, Pakistan, South Sudan). Several countries voluntarily abandoned nuclear weapons development programs (Argentina, Brazil, Egypt); several others were forced diplomatically or militarily to give up the quest (Iraq, Libya, South Korea, Syria); three former Soviet republics inherited nuclear weapons but gave them up (Belarus, Kazakhstan, Ukraine); and one country built a small arsenal before unilaterally eliminating it (South Africa). With Iran’s path to nuclear weapons blocked by the Joint Comprehensive Plan of Action (JCPOA) for at least 10 to 15 years, there are no non-nuclear weapon states currently believed to be pursuing nuclear weapons, according to U.S. government sources. And despite cases of nuclear smuggling and continuing interest of terrorist groups in acquiring nuclear weapons, no thefts of enough fissile material to build a bomb are believed to have taken place.
Success to date, but warning signs for the future The success of the non-proliferation regime to date could understandably give rise to speculation that we have seen the end of nuclear proliferation—that the number of nuclear-armed states will remain capped at single digits. But recent international developments suggest that such an optimistic assessment may be premature and that continued success cannot be taken for granted.