《新削减战略武器条约》（New START）将于 2026 年 2 月 5 日到期，象征核军备管制时代正式收场，因为它一直是美国与俄罗斯之间最后一项此类条约。条约规定双方各自上限为 1,550 枚战略核弹头；即使到期后华盛顿与莫斯科未必立刻超过这个数字（1,550），里程碑意义仍在于：自冷战最严酷时期以来，两个核超级大国首次不再受任何正式双边军控机制约束。表面上仍有残存规范：约 178 个国家遵守禁止「爆炸式」（而非电脑模拟）裂变或聚变核试验的多边安排；另有 191 个国家在理论上仍属于自 1970 年生效的《不扩散核武器条约》（NPT），其第六条要求核大国「善意」谈判以达成「全面且彻底的裁军」。

但文中主张，这些承诺在现实中正在失效。美国总统 Donald Trump 与部分顾问谈及恢复核试验，可能引发中国、俄罗斯等竞争性试验循环。与其谈裁军，现有 9 个拥核国都在「现代化」其核库；例如美国被预估将在 30 年内投入 1.7 兆美元（US$1.7 trillion，约 US$1,700 billion）升级飞弹、潜舰、轰炸机与弹头。中国正以最快速度扩充，目标是在 10 年内与美俄达到功能性对等；而 2003 年退出 NPT 的北韩也在增加库存。更棘手的是，各国同时投资更「奇特」的核武与更多战术核武（New START 完全未涵盖），而战术核武因「更可用」的错觉而更不稳定：面对来袭齐射，各国难以分辨是战术或战略攻击，因而可能在「用之或失之」逻辑下抢先发射。这种风险扩散之下，《原子科学家公报》把末日钟调到距离子夜 85 秒，称其为自 1947 年设立以来最接近灾难的时刻，甚至比古巴飞弹危机时更近。

对策上，有人主张美国应加速扩军，以同时对抗俄罗斯与中国的协同威胁；但 Richard Fontaine 认为，核战略的关键不是把对手弹头「相加」再等量匹配，而是确保即使遭到联手攻击，美国仍保有可存活的「第二击」能力，使任何第一击都必须承担自身被摧毁的代价。真正危险更可能来自误判螺旋与失控升级，甚至是自称防御性的政策也可能适得其反；例如 Donald Trump 推崇的「Golden Dome」洲际反飞弹盾若部署（即便技术与成本都存疑），可能让对手担忧美国获得免于报复的错觉，从而诱发以太空核爆摧毁拦截器与感测器，或改以潜舰与无人机等路径绕开太空。文中也指出，若美国羞辱欧亚盟友并削弱核保护伞可信度，可能迫使盟友考虑自建核武，带动连锁扩散；更多拥核国意味更高风险。尽管如此，Donald Trump 也曾把核武称为最大生存威胁，说现有核武已足以把世界毁灭「50 次、100 次」。作者主张回到谈判桌，理想是美俄中三边起步再逐步纳入其他拥核国；Vladimir Putin 表示可能愿谈，而 Xi Jinping 仍以追求对等为由尚未准备。建议是由各核领导人重申 Ronald Reagan 与 Mikhail Gorbachev 的共识：核战「不可能打赢，也绝不能打」，并逐一就各武器系统进行降风险对话。

The New START treaty expires on Feb. 5, 2026, ending the era of nuclear arms control because it is the last such treaty between the United States and Russia. It capped each side at 1,550 strategic warheads; even if Washington and Moscow do not immediately exceed that number (1,550), the milestone is that, for the first time since the coldest Cold War, the two atomic superpowers will face no formal bilateral arms-control regime. On paper, vestiges remain: about 178 countries still follow a multilateral ban on explosive (not computer-simulated) fission or fusion testing, and 191 states still, in theory, subscribe to the Nuclear Non-Proliferation Treaty (NPT) in force since 1970, whose Article VI commits major powers to negotiate in “good faith” toward “general and complete disarmament.”

In practice, the article argues, those promises are fraying. President Donald Trump and some advisers have mused about restarting nuclear testing, which could trigger competitive testing by China, Russia, and others. Instead of disarmament, all nine nuclear powers are modernizing their arsenals; the US alone is projected to spend $1.7 trillion (about $1,700 billion) over 30 years upgrading missiles, submarines, bombers, and warheads. China is expanding rapidly, aiming for functional parity with the US and Russia within a decade, and North Korea, which quit the NPT in 2003, is also growing its stockpile. Meanwhile, states are investing in more exotic nuclear delivery concepts and in tactical nuclear weapons (which New START never covered), which are destabilizing because “usable” lower-yield options blur thresholds: under an incoming volley, states may not know whether an attack is strategic or tactical and may launch under “use it or lose it” logic. Reflecting this diffusion of risk, the Bulletin of the Atomic Scientists reset the Doomsday Clock to 85 seconds to midnight, the closest since it began in 1947—closer even than the Cuban Missile Crisis.

On what to do, some argue the US should accelerate its buildup to match a combined Russia-China threat, but Richard Fontaine says nuclear safety does not come from adding adversaries’ warheads and matching totals; it comes from preserving a survivable second-strike capability that makes any first strike intolerably costly. The greater danger is a spiral of miscalculation and uncontrolled escalation, and even defensive initiatives can worsen it—for example, Donald Trump’s favored “Golden Dome” missile shield could make rivals fear US immunity and tempt them to attack space-based interceptors and sensors with nuclear detonations, or to route attacks through submarines or drones. The piece also warns that undermining allies’ confidence in the US nuclear umbrella could push them toward their own weapons, compounding proliferation risk; more nuclear states means more chances to brink. Yet Donald Trump has also called nuclear weapons the greatest existential threat, noting existing arsenals could destroy the world “50 times over, 100 times over.” The proposed remedy is renewed negotiations, ideally starting with three-way US-Russia-China talks and then widening; Vladimir Putin has signaled receptivity, while Xi Jinping is not ready while seeking parity. The article urges leaders to restate Ronald Reagan and Mikhail Gorbachev’s dictum that a nuclear war cannot be won and must never be fought, and to pursue system-by-system risk-reduction talks.