START III

START III (Strategic Arms Reduction Treaty III) refers to a proposed but ultimately unrealized arms control treaty between the United States and Russia. It was envisioned as the successor to START II, aiming to further reduce the number of deployed strategic nuclear weapons held by both nations.

The need for START III arose following the signing of START II in 1993. START II aimed to eliminate land-based multiple independently targetable reentry vehicle (MIRV) intercontinental ballistic missiles (ICBMs) and reduce overall deployed strategic warheads. However, START II faced ratification delays and never fully came into effect. Russia withdrew from START II in 2002 after the United States withdrew from the Anti-Ballistic Missile (ABM) Treaty.

Discussions regarding a possible START III began in the late 1990s and early 2000s. While specific parameters varied, the general objective was to further decrease deployed nuclear warheads and delivery systems below the levels stipulated in START II. There was also discussion about including non-deployed or reserve warheads in the treaty limitations, a significant departure from previous agreements.

Despite initial interest, negotiations for START III never progressed to a formal treaty. Several factors contributed to this, including disagreements over verification measures, the role of missile defense systems, and evolving geopolitical priorities for both the United States and Russia. The demise of START II and the lack of a follow-on agreement left a legal void in strategic arms control, prompting the negotiation of the New START treaty, which was signed in 2010 and entered into force in 2011. New START, while not START III, achieved some of the aims of the earlier proposed treaty by further reducing strategic nuclear arsenals.