UK ratchets up nuclear spending, with new warhead and delivery planes in the works

VIENNA — Britain will pour more than £63 billion ($84 billion) into its nuclear deterrent over the next four years, the government confirmed this week.

The June 30 announcement comes as part of a £15 billion ($20 billion) defense funding boost announced by outgoing Prime Minister Keir Starmer’s government. It is a continuation and concretization of the U.K.’s recent push to expand the country’s atomic arsenal. The money will fund the Dreadnought-class ballistic missile submarines and SSN-AUKUS attack boats, along with a new sovereign warhead named Astraea, according to the announcement.

The nuclear spending is a significant portion of a broader £298 billion ($398 billion) four-year spending profile meant to lift U.K. defense spending to 2.7 percent of GDP en route to NATO’s 3.5 percent target by 2035.

The figures continue an upward trend in nuclear spending that has persisted for several years. The Ministry of Defence’s Defence Nuclear Enterprise already consumed 18% of the defense budget, £10.9 billion ($14.6 billion), in 2024-25, and the Public Accounts Committee had projected that share would keep climbing to a full fifth of all military spending. The International Campaign to Abolish Nuclear Weapons has separately calculated that Britain became the world’s third-largest nuclear spender in 2025, at $12.6 billion.

The high spending associated with the nuclear program has caused criticism by some domestic advocacy groups who argue the money could be put to better use elsewhere. The government argues the nuclear bombs are essential to ensure Britain’s sovereignty, and that London plays a “unique role as the only European power to pledge our nuclear deterrent to defend our NATO allies.”

Central to the current package is Astraea, the warhead designated A21/Mk7 that the Atomic Weapons Establishment has been developing since 2020 to replace the aging Holbrook design carried on Trident II D5 missiles.

Officials and independent analysts say the replacement is less a matter of choice than necessity: Because Britain’s warheads must remain flight-certified against the American Mk4/Mk4A aeroshell shared with the U.S. Navy, the U.K. cannot simply refurbish Holbrook indefinitely once Washington moves to its own next-generation W93 warhead.

Astraea is being developed “in parallel” with the W93 and will share its Mk7 re-entry body, according to the government. The new British warhead’s estimated yield will reportedly fall somewhere between 90 and 455 kilotons, according to an analysis of publicly available information by the Nuclear Information Service, a U.K.-based nonprofit research organization. It will very likely mean a marked rise from Holbrook’s estimated 80 to 100 kilotons.

This week’s announcement also reaffirms Britain’s June 2025 decision to buy 12 F-35A jets and rejoin NATO’s Dual Capable Aircraft nuclear-sharing mission for the first time since the Cold War, a move that will see American B61-12 bombs likely based on U.K. soil, to be delivered by British aircraft if the U.S. president authorizes a strike. Similar arrangements exist with the Netherlands, Belgium, Germany, Italy and Turkey.

Britain’s nuclear modernization joins a growing chorus of signals that the world may be entering a new era of nuclear re-armament after several decades of reduction, stagnation and public opposition to nuclear bombs following the Cold War’s excesses.

Aside from London’s program, France has announced intentions to increase the size of its arsenal and extend its nuclear umbrella to other European countries, potentially deploying French nuclear bombers there, too.

China has also been engaged in a significant expansion of its arsenal, sending alarm bells ringing in Washington.

And between Russia and the U.S., who collectively hold 86% of the world’s nuclear weapons, the last remaining strategic arms reduction treaty expired in February.

Linus Höller is Defense News' Europe correspondent and OSINT investigator. He reports on the arms deals, sanctions, and geopolitics shaping Europe and the world. He holds master’s degrees in WMD nonproliferation, terrorism studies, and international relations, and works in four languages: English, German, Russian, and Spanish.

维也纳——英国政府本周证实，未来四年英国将向其核威慑力量投入超过 630 亿英镑（840 亿美元）。

6月30日的公告是即将卸任的首相基尔·斯塔默政府宣布的150亿英镑（200亿美元）国防预算增长计划的一部分。这是英国近期扩大核武库努力的延续和具体化。公告称，这笔资金将用于建造“无畏”级弹道导弹潜艇和SSN-AUKUS攻击艇，以及一种名为“阿斯特蕾亚”（Astraea）的新型自主核弹头。

核能方面的支出是总额达 2980 亿英镑（3980 亿美元）的四年支出计划的重要组成部分，该计划旨在将英国国防开支提高到 GDP 的 2.7%，从而达到北约到 2035 年 3.5% 的目标。

这些数据延续了英国核能开支持续数年的上升趋势。国防部下属的国防核能企业在2024-2025财年已消耗了国防预算的18%，即109亿英镑（146亿美元）。公共账目委员会曾预测，这一比例将继续攀升，最终达到军费开支的五分之一。国际废除核武器运动组织也单独计算得出，到2025年，英国将成为全球第三大核能开支国，核能开支将达到126亿美元。

与核计划相关的巨额开支引发了一些国内倡导团体的批评，他们认为这些资金可以更好地用于其他方面。政府则辩称，核武器对于确保英国主权至关重要，伦敦作为“唯一承诺以核威慑力量保卫北约盟国的欧洲大国”，扮演着“独特的角色”。

当前方案的核心是阿斯特拉（Astraea），即原子武器研究所自 2020 年以来一直在开发的 A21/Mk7 型弹头，旨在取代三叉戟 II D5 导弹上搭载的老旧的霍尔布鲁克（Holbrook）弹头。

官员和独立分析人士表示，更换核弹头与其说是选择问题，不如说是必要性问题：因为英国的核弹头必须保持飞行认证，以对抗与美国海军共享的美国 Mk4/Mk4A 气动外壳，所以一旦华盛顿转向使用其下一代 W93 核弹头，英国就不能无限期地翻新霍尔布鲁克核弹头。

据英国政府称，阿斯特雷亚核弹头正与W93核弹头“并行”研发，并将与其共用Mk7再入弹体。英国非营利研究机构核信息服务中心（Nuclear Information Service）对公开信息的分析显示，这款新型英国核弹头的当量估计在90至455千吨之间。这很可能意味着其当量将显著高于霍尔布鲁克核弹头估计的80至100千吨。

本周的公告还重申了英国在2025年6月购买12架F-35A战斗机的决定，并将自冷战以来首次重新加入北约的双用途飞机核共享任务。此举意味着，如果美国总统授权进行打击，部署在英国本土的美国B61-12型核弹将由英国飞机投放。英国与荷兰、比利时、德国、意大利和土耳其也达成了类似的协议。

英国的核现代化进程，与越来越多的迹象表明，在经历了冷战时期核武器过度使用带来的数十年削减、停滞和公众反对之后，世界可能正在进入核军备重建的新时代。

除了伦敦的计划外，法国也宣布有意扩大其核武库规模，并将其核保护伞扩展到其他欧洲国家，甚至可能在那里部署法国核轰炸机。

中国也一直在大幅扩充其武器库，这引起了华盛顿的警觉。

俄罗斯和美国合计拥有世界上 86% 的核武器，而两国之间仅存的战略武器削减条约已于 2 月到期。

林努斯·霍勒是《防务新闻》的欧洲记者和开源情报调查员。他报道影响欧洲乃至全球的军火交易、制裁和地缘政治。他拥有大规模杀伤性武器不扩散、恐怖主义研究和国际关系三个硕士学位，并精通英语、德语、俄语和西班牙语四种语言。