Has Britain Reduced Intelligence Sharing with the United States?

Some insiders believe it is time for Britain to reduce intelligence sharing with the United States, which has long been a cornerstone of the special relationship between the two countries. The special relationship saw an expansion on several fronts during the administration of President Donald Trump, but many in the national security community viewed the last bastion as the two nations’ approach to intelligence cooperation.

Significant cracks began to emerge between the nations after Trump’s decision in March 2025 to withhold US intelligence from Ukraine, both from its own agencies and from others in the “Five Eyes” security alliance. While Kyiv’s allies across Europe condemned Trump’s decision regarding intelligence sharing with Ukraine, Britain did not respond, with a spokesperson for British Prime Minister Keir Starmer affirming that the relationship between Britain and the US “in defense, security, and intelligence remains inextricably intertwined.”

The ties between British and American intelligence networks are so deep that unraveling them could be impossible, or replicating American contributions, according to current and former intelligence officials who have worked in various regions, speaking on the condition of anonymity about national security matters. However, experts argue that despite the complexities of the relationship, it may be necessary for Britain to start planning for what was previously unthinkable if Trump’s America continues to drift away from its older alliances and shared international goals.

Automated collective sharing of digital intelligence has become increasingly important. Britain’s standing as a relatively heavyweight in intelligence has been built over decades and was formalized with the establishment of the “Five Eyes” intelligence-sharing alliance, comprising the UK, US, Canada, Australia, and New Zealand after World War II. In the years that followed, the broad scope of joint operations and surveillance remained largely unreported until Edward Snowden, a former contractor for the US National Security Agency, leaked over 1.5 million classified documents in 2013, revealing the alliance’s operations worldwide.

The “Five Eyes” alliance has survived the leaks but has revealed “many capabilities and access” of the coalition, changing how intelligence is gathered and how some technology companies interact with governments, according to a former senior intelligence official in the UK.

There has been a relative decline over the past few decades in human intelligence collection—often referred to as HUMINT, which broadly covers the agents and assets managed by the FBI and CIA in the US and MI5 and MI6 in the UK. However, this decline has been matched by a massive rise in digital space, signals intelligence—known as SIGINT, covered by the UK’s GCHQ and the US’s NSA.

The automated collective sharing of this digital intelligence has become more critical as human intelligence “does not evolve in the same way,” according to the same former intelligence source. They added: “This integration is very deep, and it is extremely concerning to untangle it.”

Britain Still Holds Valuable Information for the US Britain continues to possess valuable assets that benefit the US, most notably its eavesdropping centers. These military and intelligence facilities, often located abroad, are used for monitoring communications. The details of these listening posts are sometimes kept under wraps, with their locations, capabilities, and the countries they monitor kept secret for national security reasons.

However, the critical data they collect makes it unlikely that the US would withdraw from the “Five Eyes” alliance, according to Neil Melvin, director of international security at the Royal United Services Institute (RUSI), a think tank specializing in defense and security. He noted that “for instance, the US relies on the ‘Aios Nicolaus’ alliance in Cyprus in the eastern Mediterranean, which is critical for Israel.”

Should the US leave the alliance, it would need to replace some of the expensive assets held by the UK, in addition to the existing US signals and intelligence bases in Britain, such as the Royal Air Force base at Menwith Hill in Yorkshire.

A British intelligence expert working in the private sector states that the best understanding of the eavesdropping centers is that they “aggregate vast amounts of raw data,” such as internet, phone, and radio data, then “analyze it using machine learning or artificial intelligence”—like keywords or sounds or addresses. They added: “Only after this mining does the information come to human eyes.”

A former senior security official in the British government emphasized that surveillance responsibilities are shared between Britain and America, meaning that intelligence is also shared. They stated: “There will come a day or a week when it is the UK’s turn, and next time it may be the US’s.”

A former high-ranking British intelligence official, who worked closely with their American counterparts, indicated that the signals intelligence community is very well integrated in the “Five Eyes” alliance. They added: “Some use American equipment operated by Britons, others do the reverse; the same goes for Australia and Canada.” They continued: “You will find Americans working at the UK’s Government Communications Headquarters (GCHQ) and Britons working at the US National Security Agency (NSA).”

The Impact of the US Withholding Intelligence from Ukraine Recent events have reminded US allies that its intelligence capabilities are unmatched. The US’s ban on sharing intelligence with Ukraine has had a tangible impact on its ability to confront Russia, particularly through the use of American technology that relies on intelligence and American contributions to function effectively.

A former senior intelligence official in the UK explained that the Trump administration’s decision to suspend Ukraine’s access to commercial satellite imagery used by the US government was a “very concerning” development, adding: “This should be a shock to the system, but it seems that everyone ignored it.”

The official added that while the UK can help analyze images gathered by the US from space, it does not possess the capability to collect them itself. They noted that any sharing from the US “can, of course, be switched on or off.”

Concerns regarding the implications of a waning American position reflect long-standing worries about its ability to disable the effectiveness of F-35 aircraft sold to its allies, including the UK, through a “kill switch.” These concerns were exacerbated by Trump’s statements when announcing the new generation of F-47 American jets. He asserted that when sold to allies, the aircraft’s capabilities might be “reduced by about 10%,” reasoning that “they might not be our allies one day, right?”

Funding British Security and Defense Innovations by the US Many British security and defense innovations have been funded by the US, providing support for the development of “dual-use” technologies—with both civilian and military applications—for America and its allies in the Five Eyes alliance. A former British intelligence official explained: “If the US wants something from UK invention these days, it simply buys it,” adding that the Defense Advanced Research Projects Agency—the US government entity that helped drive technological advances like GPS and the internet—funds UK universities and directly commissions them.

In-Q-Tel, a US company acting effectively as a venture capital firm for the CIA, has been an early-stage funder for at least 29 investments in various British technology and defense companies. The company, named after “Q,” aims to identify new commercial technologies that could contribute to the national security of the US, the UK, Australia, and their allies.

At least 15 of these investments have been identified, ranging from drone manufacturers or graphene-based electronics— a carbon material that is 200 times stronger than steel—to AI solutions and maritime robotics.

While the UK has experienced significant American capital acquisitions, the latest being the acquisition of Darktrace for $5.3 billion in 2024, once a darling of the British tech scene, there are some safeguards in place to keep the technology protected, even from allies.

In February, the British government granted ESCO Maritime Solutions a security clearance to purchase Ultra PMES Limited, the British supplier of naval defense systems. This approval was subject to certain stipulations, such as appointing a British government director and a chief security officer, and maintaining powers to compel companies to support the UK’s defense and security as necessary.

Nonetheless, the integration of American companies into British defense, intelligence, and civilian infrastructure is critical, and sometimes without equivalent public protections. Palantir, a data analytics company that was one of In-Q-Tel’s early success stories, has contracts in Britain that include data from the central government, the National Health Service, the armed forces, and police.

Other major American companies are similarly integrated. For instance, Elon Musk’s Starlink satellites help provide internet service to rural areas in Britain, while the Ministry of Defense has contracts with the American defense tech start-up Anduril. The same former intelligence official noted that “intelligence agencies use Palantir,” adding that GCHQ entered into a deal with Amazon in 2021 to store its data on the cloud “because they considered it would be as secure as anything else, and doing so would be cheaper.”

For decades, Britain believed that integrating American technology was “very clever cooperation,” as they put it, because the relationship between the two countries is “a lasting relationship we can rely on, and more effective than relying on the EU, which is constrained by multiple conditions. We were wrong.” While American access to Britain is not a new phenomenon, the overtly political nature of the current group of tech billionaires linked to the White House under Trump has caused concern in some parts of the country’s intelligence community.

Musk’s interest in influencing British and European politics was evident, as was the clear ideological extremity of Palantir founder Peter Thiel—who financed and directed Vice President JD Vance—according to a figure in the UK intelligence community who now works in the private sector.

Preparing for the Worst Those who have closely observed the special relationship through intelligence channels are divided on what should be done, but most agree that the most concerning trends arise from America’s softening stance towards Russia. An intelligence official working in the private sector stated: “They voted with Russia, Iran, North Korea, and China on Ukraine at the UN—something unimaginable a year ago.”

Melvin, from the Royal United Services Institute (RUSI), views the suspension of intelligence sharing with Ukraine as a warning sign for American intelligence partners. He added: “We have not reached a crisis yet, but there is a new level of caution in the relationship.” However, the British government’s general stance has been one of not criticizing Trump.

A former senior intelligence official confirmed: “There is still significant resistance within the British government to prepare for the truth that trust in the US has faded. Some hope to regain it, and they think they can limit the damage, which really won’t happen, not realizing it has already occurred.” Another former senior intelligence official affirmed: “You have to hope for the best but prepare for the worst,” with future possibilities including the US withdrawing from NATO and “sliding into unreliability as an ally.”

However, they added that the relationship of the Five Eyes is “deeply rooted and governed differently” to the extent that it would be “the last thing in the transatlantic relationship to collapse,” as it is managed by “professional intelligence heads, not politicians.” They said: “The US cannot be expelled from the Five Eyes alliance. It would be like expelling England from the UK—it simply would not work, and the entire concept would collapse.”

Some others appear more optimistic about Britain’s prospects, with a former British minister stating: “America does not hold all the cards, and I saw this during my time in government: Our people have adapted greatly to this feeling of American power, to the extent that we have long stopped flexing our muscles with them. I had to remind people that it is a partnership, not a relationship of dependency. There is no need to redefine or dismantle it; all we need to do is assert ourselves as an equal partner.”

As for its position in NATO, America’s enduring stature within the intelligence community has largely been a result of the financial and technological power it contributes.

Implications of America’s Withdrawal from Intelligence Cooperation “Regarding the approximate size of the Five Eyes alliance, if we assume that the US invests the same amount of total resources as the other four countries of the Five Eyes combined, we wouldn’t be far wrong,” said a former intelligence official who worked closely with America. Several former intelligence officials noted that such a close, trust-based relationship with an ally would be the hardest thing for Britain to replace should the US withdraw from intelligence relations.

Even with a slight improvement in Britain’s relations with Europe under Starmer, it will take time to build the same level of understanding and common practices that it has with the US with any other nation. For instance, Melvin pointed out that despite the robustness of British-French relations, the level of mutual trust between them in intelligence sharing is not equal. He added that Japan has failed for years to achieve a sufficient level of “intelligence integrity” within its security agencies, despite discussions about joining the Five Eyes as a sixth member.

However, the potential exit of Trump’s America from the traditional international order offers the UK a chance to take on a leadership role. While it cannot match American financial influence, the UK still holds some respect in Europe, a respect that America is rapidly losing. Across Northern and Eastern Europe, America’s reputation has faded. The old NATO alliance has vanished—it won’t disappear, but it will dissolve,” said a former intelligence official who worked with NATO allies. “In the eyes of the numerical majority of NATO countries, the UK is the only nation capable of replacing America.”

The official added: “Trust walks in on foot and leaves on horseback. It will take a long time to rebuild it.” “This does not mean that NATO as an institution is dead or valueless; quite the opposite,” they stated, “but the old NATO structure, which relied on trust that the US would come to Europe’s rescue in the event of a catastrophic attack by the Russians, is now without any credibility.”

The former official noted that Britain’s diligent efforts to form a “coalition of the willing” for Ukraine, with NATO at the heart of the discussions, despite threats from Vladimir Putin, show that Starmer and his Defense Minister Jon Healy recognize its value as an institution. They affirmed that NATO’s core value lies in creating space for countries to share intelligence and build trust.

The European Union has nothing like this whatsoever, while NATO does—not only with its members but also with its partners, including Japan and Australia. NATO is already a global organization; it just needs to be formalized. The UK is already working to strengthen relationships within NATO, leading almost weekly summits with France regarding the future of Ukraine and European defense capabilities.

Despite Secretary of State Marco Rubio insisting in April 2025 that the US is “active in NATO as it always has been,” recent moves have shown that this might not always be the case—with the question remaining before the cash-strapped and unpopular Labour government: “Can Britain increase its activity?”