Nuclear non-proliferation refers to diplomatic, legal, and economic efforts to stop the spread of nuclear weapons beyond the current nine nuclear-armed states. The Nuclear Non-Proliferation Treaty of 1968, signed by 191 countries, prohibits non-nuclear states from acquiring nuclear weapons and commits nuclear states to eventual disarmament. Iran signed the NPT as a non-nuclear state. Its uranium enrichment program—which can produce both fuel and weapons material—has been the focus of international negotiations since 2003. The 2026 U.S.-Iran nuclear talks seek to prevent Iran from crossing the threshold to weapons-grade capability.