SIPRI-迈向更大的核约束：提高使用核武器的门槛（英文）-2020.5-24页_279kb

Summary: Towards Greater Nuclear Restraint: Raising the Threshold for Nuclear Weapon Use

Core Content

This report explores the risks associated with a perceived or actual lowering of the nuclear threshold among the five major nuclear weapon states (NWS): China, France, Russia, the United Kingdom, and the United States. It argues that the increasing ambiguity in nuclear doctrines and the expansion of nuclear roles in military planning have raised concerns about the stability of the international security order.

Main Viewpoints

• Nuclear Deterrence and Restraint: Nuclear deterrence relies on the credible threat of retaliation to prevent aggression, but its stability is undermined by the possibility of first use. The report emphasizes that maintaining nuclear restraint is crucial for international security.

• Uncertainty and Technological Developments: The report highlights how technological advancements, political tensions, and the erosion of arms control agreements have increased uncertainty regarding the threshold for nuclear weapon use. This has led to a shift in nuclear doctrines and capabilities that may signal a lower threshold for nuclear engagement.

• First Use Scenarios: The report identifies several scenarios in which nuclear weapons might be used first, including:

  • Conventional Conflict: A losing side may use nuclear weapons to compensate for conventional inferiority or to end a conflict.
  • Preventive Strike: The use of nuclear weapons to neutralize an adversary's nuclear capabilities before they can be used.
  • Escalation to De-escalate: A doctrine where limited nuclear use is intended to deter further aggression, though this is not officially acknowledged by Russia.

• Extended Deterrence: The right to first use is also linked to extended deterrence, where nuclear-armed states protect their allies. This has been a key reason for the United States rejecting a no-first-use (NFU) policy, as it could undermine the credibility of its nuclear guarantee to allies.

• Modernization and Dual-Use Capabilities: The modernization of nuclear forces, including the development of low-yield nuclear weapons and dual-use delivery systems, has contributed to the perception of a lower nuclear threshold. These capabilities may be misinterpreted during crises, increasing the risk of accidental or unauthorized use.

• Strategic Stability Concerns: The report underscores that even if nuclear weapons are not used, the mere perception of a lower threshold can lead to increased militarization and instability, as adversaries may feel compelled to respond with their own nuclear posturing or arms build-up.

Key Information

• China: The only NWS with an official NFU policy. Its nuclear forces are modernizing, particularly its sea-based deterrent, but it maintains a defensive posture.

• United States: Has moved away from NFU, emphasizing the development of low-yield nuclear weapons and flexible deterrence options. This is seen as a response to perceived Russian nuclear posturing.

• Russia: Has not officially adopted an NFU policy. It has been accused of promoting the 'escalate to de-escalate' doctrine, though it denies this. Its military exercises and dual-use capabilities have fueled Western concerns.

• United Kingdom and France: Both maintain strategic nuclear capabilities but also support the idea of limited nuclear strikes to avoid being 'self-deterred' by an all-or-nothing approach.

• Preventive Strike and Counterforce: These are seen as part of the broader strategy to reduce the catastrophic consequences of nuclear war, but they also lower the perceived threshold for nuclear use.

• Missile Defenses and Strategic Stability: The development of missile defense systems by the US has raised concerns among China and Russia, as they may perceive these as undermining their retaliatory capabilities.

• International Dialogue: The report advocates for a broader international discussion on nuclear doctrines, building on the P5's agreement in 2019 to enhance dialogue on nuclear policies and doctrines under the Non-Proliferation Treaty (NPT) framework.

Recommendations

• Reduce Doctrinal Ambiguity: Clarify nuclear doctrines to reduce the risk of misinterpretation and unintended escalation.

• Enhance Credible Assurances: Provide more transparent and credible assurances that nuclear weapons will only be used as a last resort.

• Promote Strategic Stability: Encourage arms control measures and dialogue to restore confidence and prevent the perception of a lower nuclear threshold.

Conclusion

The report concludes that while the actual use of nuclear weapons remains rare, the increasing willingness to consider their use in a wider range of scenarios, combined with the development of new capabilities, poses significant risks to global stability. It calls for greater restraint and a renewed commitment to dialogue and transparency among nuclear-armed states to ensure the continued effectiveness and stability of nuclear deterrence.