Ambassador: UK ramps up defense capabilities, for a stronger transatlantic security posture

Ambassador Peter Mandelson has represented the United Kingdom in Washington since February 2025. (British Embassy)

Editor’s Note: Peter Mandelson is the United Kingdom’s ambassador to the US. In the below exclusive opinion piece, Mandelson, who took over the role in February, discusses London’s new defense document, released earlier this week. 

On Monday, the United Kingdom unveiled the new Strategic Defence Review. This comprehensive review will profoundly transform the UK’s warfighting readiness, backed by our biggest contribution to NATO since its creation.

We have committed to the largest sustained increase in defense spending since the end of the Cold War to build a fighting force that is more integrated, more ready, more lethal than ever before, following a root and branch review of our defense capabilities.

The world has changed. We are in a new era of threat, which demands a new era for British defense. Our adversaries are working more in collaboration with one another, while new technologies are changing how war is fought.

The threat we now face is more serious and less predictable than at any time since the Cold War. We face war in Europe, growing Russian aggression, new nuclear risks, and cyber attacks on any day. Drones now kill more people than traditional artillery in the war in Ukraine, and whoever gets new technology into the hands of their Armed Forces the quickest will have the advantage.

A New Vision For The UK’s Armed Forces As America’s Preeminent Partner

The UK has a new vision for how its Armed Forces should be conceived: a combination of conventional and digital warfighters, with the power of drones, AI and autonomy complementing the “heavy metal” of tanks, artillery, ships, and fighter jets.

We are determined to make our allies safer too. We will continue to strengthen our partnership with the United States, our closest defense and security ally. There are 900 UK military personnel and civil servants across thirty US states ensuring Day One operational readiness, whilst US forces at six Royal Air Force sites provide America with European access. It’s this speed and willingness to act together, demonstrated recently in our joint response to Houthi attacks on Red Sea shipping, that cements the relationship.

At the same time, It has been made crystal clear that European defense must step up and rebalance for our collective security, and the UK has taken that challenge seriously. Our approach is to become less dependent on America, while remaining inseparably linked to America.

This is exemplified by AUKUS, our trilateral security partnership with Australia and America, which connects Euro-Atlantic security with Indo-Pacific allies to strengthen collective security in both regions. It will deliver advanced nuclear-powered submarines and catalyze technology sharing on other advanced capabilities — exactly the kind of creative statecraft the 21st Century demands.

The SDR takes a major step in this direction, outlining plans to build up to a dozen new attack submarines alongside our £15 billion ($19 billion) warhead program exemplifies this new thinking. But this isn’t simply about submarines or weaponry — it’s about moving to warfighting readiness with a more lethal integrated force equipped for future conflicts, whilst maintaining our NATO-first approach to western security leadership.

US-UK Innovation For Air, Land And Sea Superiority

We will become one of NATO’s fastest-innovating nations, ensuring our military forces have the technological and military capabilities to secure long-term strategic advantage. For example, our aircraft carriers will be transformed into the first European hybrid air wings with fast jets, long-range weapons, and drones.

This new era demands not just spending more, but spending better, investing in advanced manufacturing and high-skilled employment. The United Kingdom and United States are the only two Western nations with trillion-dollar technology ecosystems combined with unparalleled talent and research capabilities in our universities and corporations. We must combine our strengths to maintain the Western alliance’s strategic edge, delivering the best kit and technology into the hands of our front-line forces at speed.

As we have seen in Ukraine, the timelines for new battle technology are no longer measured in months and years, but hours and days. The focus on innovation — harnessing drones, data and digital warfare lessons from Ukraine — reflects an understanding of how modern security challenges must be met. This isn’t just about conventional capabilities, but about building the technological advantage that makes our Armed Forces stronger and safer.

The US-UK defense and intelligence co-operation is the broadest, deepest and most advanced of any two countries. We have stood shoulder to shoulder for more than 100 years but we cannot rest on past glories. With this landmark defense review, British Armed Forces will bring to bear cutting-edge capabilities to our partnership with America, to defend our shared interests and values in the critical decades ahead.

Peter Mandelson was appointed UK Ambassador to the United States of America in December 2024. Peter has held a range of senior positions in government under Prime Minister Tony Blair and later Gordon Brown. He was First Secretary of State and Secretary of State for Business, Innovation and Skills from 2008 to 2010. He was Secretary of State for Business and Trade (1998) and Secretary of State for Northern Ireland (1999 to 2001).