Britain and France, Europe’s two nuclear-armed powers, unveiled the Northwood Declaration on 10 July, pledging for the first time to coordinate the employment of their independent nuclear forces. Signed at the UK’s Northwood headquarters by Prime Minister Keir Starmer and President Emmanuel Macron, the accord states that “there is no extreme threat to Europe that would not prompt a response by our two nations.” Under the declaration, each country retains full sovereign control of its arsenal, yet the deterrents “can be coordinated.” A UK-France Nuclear Steering Group, led by the Cabinet Office and the Élysée, will oversee policy, capability and operational planning. Starmer called the step “truly historic,” while Macron said the arrangement signals to partners and adversaries alike that Paris and London will act jointly to protect the continent. The move brings closer alignment of stockpiles that together total roughly 500 warheads—about 225 in Britain and 290 in France. Paris currently spends about €5.6 billion a year on its deterrent. Officials framed the pact as a response to a more uncertain security environment, heightened by Russia’s war in Ukraine and questions over future U.S. commitments to Europe. In a parallel announcement, the two governments ordered new Franco-British Storm Shadow/SCALP-EG cruise missiles. Missile maker MBDA said full-rate production will resume in 2025, ending a 15-year hiatus and replenishing inventories depleted by deliveries to Kyiv. The missile order and the nuclear accord form part of a broader effort by London and Paris to deepen defence cooperation and modernise Europe’s high-end military capabilities.