【转载自“中国国际法前沿”公众号，感谢授权】
日前，中国、俄罗斯、美国、英国、法国在联合国大会发表联合声明，重申反对去年7月联合国谈判会议通过的《禁止核武器条约》。这一联合声明不仅是安理会五大常任理事国共同政治立场的宣示，在国际法上也有着特殊的意义。
诚然，无核世界理念正得到越来越广泛的响应和支持。从根本上说，全面禁止和彻底销毁核武器，消除核战争威胁，符合全人类的共同利益，是世界各国的共同夙愿，但这并非一蹴而就的目标。中国政府一向积极致力于推进国际核裁军进程，并主张应遵循“维护全球战略稳定”和“各国安全不受减损”原则，循序渐进加以推进；相关进程必须在现有国际裁军和防扩散机制下处理。
2017年3月，在一些激进反核国家强行推动下，《禁止核武器条约》谈判进程启动，并在不到4个月时间内完成谈判。《禁止核武器条约》至今仅有19个缔约国，尚未生效，缔约国中也无一拥有核武器。但是，作为迄今第一项全面禁止核武器的条约，其诞生本身及后续发展均可能带来一系列国际法上的问题，特别是其对关于核武器合法性的习惯国际法规则的影响。有观点认为，1996年国际法院“核武器合法性问题”咨询意见之所以并未认定存在绝对禁止核武器的习惯国际法，一项重要理由就是当时尚未缔结禁止核武器的普遍性国际条约，而《禁止核武器条约》的出现可能改变这一状况。
1968年《不扩散核武器条约》（NPT）是现行核不扩散体系的基石。安理会五常同时也是NPT第九条认可的“有核武器国家”。安理会五常法律顾问团队始终高度关注缔结《禁止核武器条约》可能对现行相关国际规则带来的影响。安理会五常发表联合声明公开反对《禁止核武器条约》，从法律上看，是运用习惯国际法形成及效力范围的规则设置两道防线，防止该条约冲击现有相关国际规则和合法拥核国家的正当权益：
一是作为“特别受影响国家”（specially affected States）表明立场，阻止该条约被认为得到广泛接受而形成新的习惯国际法规则。联合国国际法委员于今年拟定的《习惯国际法的识别》结论草案被认为准确反映了相关国际法规则。结论草案第8项指出，“有关惯例必须具备一般性，即必须足够广泛和有代表性，还必须是一贯的”。该结论的评注吸纳包括中国在内的有关国家意见指出，在评估“一般性”时，必须要考虑到的一个因素是，“特别参与有关活动或最有可能关注所称规则的国家（特别受影响国家）在多大程度上参与了惯例”。安理会五常作为现行国际法上仅有的合法拥有核武器的国家，在核武器合法性问题上，显然属于结论草案评注所指“特别受影响国家”。安理会五常此次联合声明中也尤其表明“不接受任何关于该条约有助于形成习惯国际法的主张”。这一主张的意义在于，将来即使《禁止核武器条约》生效，并被相当数量国家接受，只要安理会五常作为“特别受影响国家”表示反对，就很难认为条约有关规定得到了广泛接受，从而阻止其形成习惯国际法规则。
二是明确表明安理会五常是“持续反对者”（persistent objectors），即使《禁止核武器条约》有关内容形成习惯国际法规则，也对安理会五常无约束力。《习惯国际法的识别》结论草案第15项指出，如果一国在一项习惯国际法规则的形成过程中坚持对其表示反对，则该规则形成后不可适用于该国。条件是该反对立场必须明确表示、向其他国家公开并始终坚持。这就是习惯国际法著名的“持续反对者”规则。安理会五常以发表联合声明及其他方式持续表明反对立场，可以充分满足“持续反对者”条件。因此，即使认为安理会五常作为“特别受影响国家”未能阻止《禁止核武器条约》有关内容形成习惯国际法规则，那么安理会五常作为“持续反对者”，仍可不受有关规则的约束。
当然，除了习惯国际法问题，《禁止核武器条约》还存在其他法律问题。比如：该条约承认NPT“作为核裁军和不扩散制度基石”的地位，但该条约将核武器全面非法化，与NPT承认安理会五常合法拥核，以及以NPT为基石构建的无核区条约等现有规则和机制存在根本冲突。《禁止核武器条约》还规定了保障监督机制，其与NPT框架下的保障监督机制是何种关系也并不明确。这些问题还需进一步关注和研究。
后附安理会五常联合声明英文全文，供参考。
UNGA 73, FIRST COMMITTEE
THEMATIC DEBATE
(NUCLEAR WEAPONS)
We, the nuclear weapon States recognized by the Treaty on the Non-Proliferation of Nuclear Weapons, reaffirm our commitment to the Treaty, in all its aspects, fifty years since its signature.
This landmark Treaty has provided the essential foundation for international efforts to stem the threat that nuclear weapons would spread across the globe, and has thereby limited the risk of nuclear war. It has provided the framework within which the peaceful uses of nuclear technology – for electricity, medicine, agriculture and industry – could be promoted and shared, to the benefit of humanity. And by helping to ease international tensions and create conditions of stability, security and trust among nations, it has allowed for a vital and continuing contribution to nuclear disarmament.
We pledge our full and continued support for the work of the International Atomic Energy Agency (IAEA), which plays a critical role in NPT implementation, both in promoting the fullest possible cooperation on the peaceful uses of nuclear technology and in applying safeguards and verifying that nuclear programmes are exclusively for peaceful purposes. We emphasise the need to further strengthen the IAEA safeguards system, including the universalisation of the Additional Protocol.
We remain committed under the Treaty to the pursuit of good faith negotiations on effective measures related to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control. We support the ultimate goal of a world without nuclear weapons with undiminished security for all. We are committed to working to make the international environment more conducive to further progress on nuclear disarmament.
It is in this context that we reiterate our opposition to the Treaty on the Prohibition of Nuclear Weapons. We firmly believe that the best way to achieve a world without nuclear weapons is through a gradual process that takes into account the international security environment. This proven approach to nuclear disarmament has produced tangible results, including deep reductions in the global stockpiles of nuclear weapons.
The TPNW fails to address the key issues that must be overcome to achieve lasting global nuclear disarmament. It contradicts, and risks undermining, the NPT. It ignores the international security context and regional challenges, and does nothing to increase trust and transparency between States. It will not result in the elimination of a single weapon. It fails to meet the highest standards of non-proliferation. It is creating divisions across the international non-proliferation and disarmament machinery, which could make further progress on disarmament even more difficult.
We will not support, sign or ratify this Treaty. The TPNW will not be binding on our countries, and we do not accept any claim that it contributes to the development of customary international law; nor does it set any new standards or norms. We call on all countries that are considering supporting the TPNW to reflect seriously on its implications for international peace and security.
Rather, we urge all States to commit to the continued success of the NPT: to ensure compliance, to promote universalisation, to ensure the highest standards of non-proliferation, and to respond to ongoing and emerging proliferation challenges, wherever they occur. In this context our five countries reiterate our commitment to continue our individual and collective efforts within the NPT framework to advance nuclear disarmament goals and objectives.
整理、责编：鄢紫琪
（外交学院国际法系2016级本科生）
外交学院国际法研究所
外交学院法律外交研究中心
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