Background and Context

• Negotiated between the United States and the Soviet Union during the final phase of the Cold War.
• Signed on 31 July 1991 in Moscow.
• Entered into force on 5 December 1994 and remained valid until 5 December 2009.
• After the dissolution of the Soviet Union, implementation responsibilities were assumed by Russia, Ukraine, Belarus, and Kazakhstan under the Lisbon Protocol.
• Represented a transition from arms limitation to enforceable strategic arms reduction.

Objectives

• To achieve substantial and verifiable reductions in strategic offensive nuclear arms.
• To enhance strategic stability and reduce the likelihood of nuclear confrontation.
• To institutionalize transparency and predictability in bilateral nuclear relations.
• To support global non-proliferation norms and post-Cold War confidence-building.

Scope and Numerical Limits

Warhead Ceiling

• Each party was limited to a maximum of 6,000 accountable strategic nuclear warheads.
• Sub-limits were imposed on heavy intercontinental ballistic missiles (ICBMs).
• Restrictions applied to missiles equipped with multiple independently targetable reentry vehicles (MIRVs).

Delivery Vehicle Ceiling

• A maximum of 1,600 strategic nuclear delivery vehicles, including:
  • Intercontinental ballistic missiles (ICBMs).
  • Submarine-launched ballistic missiles (SLBMs).
  • Heavy bombers.

Counting Rules

• Detailed attribution rules assigned a specific number of warheads to each missile and bomber type.
• Ensured transparency and parity in force calculations.
• Addressed technical distinctions in MIRV configurations and launcher classifications.

Verification and Compliance Mechanisms

START I established an extensive and intrusive verification framework.

Transparency Measures

• Comprehensive data exchanges on force structures and deployments.
• Advance notifications regarding movements, eliminations, and changes in status of strategic systems.

On-Site Inspections

• Baseline inspections to confirm declared data.
• Short-notice inspections at operational, storage, and elimination facilities.
• Continuous monitoring at designated production facilities.

Technical Verification

• Sharing of telemetry data from ballistic missile test launches.
• Recognition of national technical means such as satellite surveillance.
• Prohibition of interference with verification systems.

Strategic and Political Significance

• First treaty mandating deep, legally binding reductions in deployed strategic nuclear weapons.
• Contributed to the denuclearization of Belarus, Kazakhstan, and Ukraine.
• Reinforced commitments under the global non-proliferation regime.
• Marked a structural shift from competitive accumulation to regulated reduction of strategic arsenals.
  

START I remains a cornerstone in the evolution of post-Cold War strategic arms control due to its scale of reductions and its rigorous verification architecture.