LONDON — The U.K.’s special relationship with the United States has been stretched on several fronts by President Donald Trump’s new administration, but many in the national security community considered the last bastion to be the countries’ approach to intelligence.
Recently, however, substantial cracks have begun to appear even there.
First, Trump ordered last month that American intelligence not be shared with Ukraine, either by its own spy agencies or by other countries in the Five Eyes security alliance. Then, U.S. national security adviser Michael Waltz inadvertently added a journalist to a conversation on the encrypted messaging app Signal that openly discussed American military action in Yemen, in an eye-opening insight into how lax current officials are with state secrets.
While Trump’s decision on intelligence-sharing with Ukraine was condemned by Kyiv’s allies around Europe, Britain did not retaliate, with U.K. Prime Minister Keir Starmer’s spokesperson stressing that Britain’s relationship with the U.S. “on defense, security and intelligence remains inextricably entwined.”
The links between Britain and America’s intelligence networks go so deep that it may be impossible to untangle them, or to replicate the U.S. contribution, according to current and former intelligence officials who have worked across the regions and were granted anonymity to speak candidly to L’Observatoire de l’Europe about areas of national security.
But the experts say that despite the intricate nature of the relationship, it may be necessary for Britain to begin planning for the previously unthinkable if Trump’s America continues to depart from its oldest alliances and once-shared international aims.
Britain’s status as a comparative heavyweight in the intelligence sphere goes back decades, having been formalized in the establishment of the Five Eyes intelligence-sharing alliance of the U.K., U.S., Canada, Australia and New Zealand following World War II.
In the years since, the vast scale of joint operations and surveillance went largely unreported until NSA whistleblower Edward Snowden leaked over 1.5 million classified documents in 2013 and unearthed the alliance’s work across the globe.
Five Eyes survived the leaks, but they revealed “a lot of the capabilities and access” of the alliance, changing the way intelligence was collected and how some tech companies behaved toward governments, according to one former senior U.K. intelligence official.
There has been a relative decline over the last few decades in the gathering of human intelligence — often referred to as HUMINT, which broadly covers agents and assets run by the FBI and CIA in the U.S. and MI5 and MI6 in the U.K. But that drop has been matched by a meteoric rise in its digital cousin, signals intelligence — named SIGINT, covered by the work of Britain’s GCHQ and America’s NSA.
The automated bulk sharing of this digital intelligence has become more important given that human intelligence “doesn’t scale in the same way,” the same former intelligence source said. “That is deeply, deeply integrated, and it’s deeply disruptive to disentangle that,” they added.
Britain still has important assets that are of use to America — chief among them its listening posts. These are military and intelligence facilities, often overseas, used to monitor communications. The details of listening posts are sometimes classified, with their locations, capabilities or which nations they monitor kept secret for national security reasons.
But the crucial data they collect makes it unlikely the U.S. would ever leave Five Eyes, according to Neil Melvin, director of international security at the Royal United Services Institute (RUSI), a defense and security think tank. “For example, the one in Cyprus (Ayios Nikolaos) — the U.S. relies on that for the East Mediterranean, which is very important because of Israel,” he pointed out.
If the U.S. left the alliance, “they would also have to replace some very expensive assets that the U.K. has,” as well as U.S. signals and intelligence bases located in Britain, such as RAF Menwith Hill in Yorkshire — referred to by locals as “the golf balls.”
One figure in the U.K. intelligence community now working in the private sector said that listening posts are best understood as “hoovering up huge amounts of raw data” such as internet, telephone and radio traffic, and then “picking through it using machine learning or AI to pick up the signal from the noise” — such as key words, voices or addresses. “Only after that sifting does it really ever get in front of the eyes of a human being,” they added.
A former U.K. government security official added that responsibilities for monitoring are shared by Britain and America, which means the intelligence is also shared. “One day or one week it will be the U.K.’s turn, the next time it will be the U.S.’s,” they said.
A separate former senior U.K. intelligence official who has worked closely with American counterparts noted that the signals intelligence community is particularly well integrated in Five Eyes. “Some are using U.S. equipment manned by Brits, some are the other way around; the same with Australia and Canada,” they said, adding: “You’ll find Americans working at GCHQ and Brits working in NSA.”
Recent events have reminded U.S. allies that its intelligence capabilities can’t be matched. The U.S. intelligence-sharing ban for Ukraine had a material impact on its ability to fight Russia, most notably with its use of U.S. technology that needed American intelligence and input to properly function.
The Trump administration’s decision to suspend Ukraine’s access to commercial satellite imagery used by the U.S. government was a “quite worrying” development, according to the same former senior U.K. intelligence official, who added: “That should be a bit of a shock to the system, but everyone seems to have ignored it.”
While the U.K. can help analyze imagery the U.S. collects from space, it doesn’t have the capability to collect it itself, the official said. And any sharing from the U.S. “can, of course, also be turned on or turned off.”
Concerns about the implications of falling out of America’s good graces are echoed in long-running fears that it has the ability to hamper the effectiveness of the F-35 jets sold to allies, including the U.K., through some form of “kill switch.” Those fears were exacerbated by Trump’s comments when announcing the contract for America’s next-generation F-47 aircraft. When sold to allies, he said, the jet’s capabilities might be toned down by “about 10 percent,” as “someday, maybe they’re not our allies, right?”
Downing Street was approached by L’Observatoire de l’Europe for comment.
Many of Britain’s security and defense innovations have been funded by the United States, providing support for the development of “dual-use” technology — with civilian and military applications — for America and its Five Eyes allies.
“If the U.S. wants something of the U.K.’s invention these days, it simply buys it,” said one former British intelligence official, adding that the Defense Advanced Research Projects Agency (DARPA) — the U.S. government agency that helped push through technological advances like GPS and the Internet — funds and commissions U.K. universities directly.
In-Q-Tel, an American company that effectively operates as a venture capital firm for the CIA, has been an early-stage funder in at least 29 investments in various British tech and defense companies. Reportedly named after the spy gadgetmaster “Q” from James Bond, it aims to identify new commercial technology that could contribute to the national security of the U.S., the U.K., Australia and its allies.
L’Observatoire de l’Europe has identified at least 15 of these investments, which range from manufacturers of drones or electronics made from graphene — a carbon-based material 200 times stronger than steel — to artificial intelligence solutions and marine robotics.
While the U.K. has seen some of its homegrown talent snapped up by the might of American capital — most recently with last year’s $5.3 billion acquisition of Darktrace, once the darling of the British tech scene — there are some safeguards to keep technology protected, even from allies.
In February, the government gave security clearance for U.S. engineering group ESCO Maritime Solutions to buy out British naval defense supplier Ultra PMES Limited. This came with caveats, such as appointing a British government director and chief security officer, and retaining powers to compel the companies to support the U.K.’s defense and security if required.
However, the integration of U.S. companies into Britain’s defense, intelligence and civilian infrastructure is substantial, sometimes without similar publicly declared protections. Palantir, a data analytics company that was one of In-Q-Tel’s most successful early investments, has contracts in Britain including with central government data, the NHS, the armed forces and the police.
Other vast U.S. companies are similarly embedded. For example, Elon Musk’s Starlink satellites help provide internet access for rural parts of Britain, and the Ministry of Defense has contracts with American defense-tech startup Anduril.
“The intelligence services use Palantir,” said the same former intelligence official, adding that GCHQ in 2021 struck a deal with Amazon for the storage of its data on the cloud “because it considered that they would be as secure as anything, and would be cheaper to do it.”
Britain for decades thought that embedding American tech was a “very clever collaboration,” they said, because the relationship between the two countries was a “permanent one that we could rely on, and was a more effective one than relying on the EU, which has a variety of strings attached to it. We were wrong.”
While the access of American companies to Britain is nothing new, the hyper-political nature of the current crop of tech billionaires with ties to Trump’s White House has caused disquiet in some parts of the country’s intelligence community.
Musk’s interest in influencing British and European politics has been explicit, and Palantir founder Peter Thiel — who helped fund and mentor Vice President JD Vance — is also “obviously highly ideological,” said one figure in the U.K. intelligence community now working in the private sector.
“Musk and Thiel, Starlink, Palantir, Anduril, anything like that, in my view, really needs to be purged from our systems no matter the cost, because you’ve got an oligarchic, authoritarian system emerging and those people are right in the middle of it.”
Those who have seen the special relationship up close on intelligence are split as to what has to be done, with most agreeing the most concerning moves come from America’s softening stance toward Russia.
“They voted with Russia, Iran, North Korea and China on Ukraine in the United Nations — it’s just unthinkable a year ago,” said the intelligence figure working in the private sector.
RUSI’s Melvin told L’Observatoire de l’Europe that the cessation of intelligence sharing with Ukraine had been a “flashing amber light” to U.S. intelligence partners. “We’re not yet in a crisis, but there is a new level of caution in the relationship.”
But the stance of the British government has been, broadly, not to criticize Trump. “There’s still a significant resistance in Whitehall, particularly, to being prepared to discuss the fact that the trust in the U.S. has gone,” said one former senior intelligence official. “Some are hoping that it can be gotten back, and that they can limit the damage and it won’t really happen, not understanding that it already has happened.”
“You have to hope for the best, but prepare for the worst,” another former senior intelligence official said, with future possibilities including a U.S. withdrawal from NATO and its “descent into unreliability as an ally.”
However, they added, the Five Eyes relationship is so “deeply embedded and differently governed” that it will be “the last thing of the transatlantic relationship to unravel,” as it is run by “professional intelligence heads, not by politicians.”
“You can’t kick America out of Five Eyes,” they said. “It’d be like kicking England out of the United Kingdom — it doesn’t work, the whole concept falls apart.”
Others are more bullish about Britain’s prospects, with one former U.K. minister involved in security telling L’Observatoire de l’Europe: “America doesn’t hold all the cards, and I saw this during my time in government: Our people have been so conditioned by this sense of America’s power, we gave up flexing our own muscles with them so long ago.
“I had to remind people that it is a partnership, not a subservient relationship. There’s no need to redefine it or untangle it, we just need to assert ourselves as an equal partner.”
As with its position in NATO, America’s enduring place in the intelligence community has been in large part due to the monetary and technological might it contributes.
“On rough orders of magnitude for Five Eyes, if you worked off the idea that the U.S. puts in the same in terms of overall resources as the other four of the five eyes combined, you wouldn’t be far wrong,” said one former intelligence official who has worked closely with America.
Several former intelligence officials said that such a close, trusting relationship with an ally would be the most difficult thing for Britain to replace were America to withdraw from the intelligence relationship.
Even with Britain’s slight improvement of relations with Europe under Starmer, it would take time to build the same type of understanding and shared practices it has with the U.S. with anyone else.
For example, Melvin noted that though the U.K.-France relationship is strong, there is not the same level of trust on sharing intelligence. Similarly, he added that Japan has for years been unable to get up to an adequate level of “intelligence hygiene” in its security apparatus, despite talk of its becoming a sixth member of Five Eyes.
But the potential departure of Trump’s America from the standard international order does provide the U.K. with an opportunity to step into the leadership role. And although it cannot match America’s financial clout, the U.K. still carries some of the respect in Europe that America is quickly losing.
“All across the Nordic and East European countries, the American reputation is gone. The old NATO has gone — it’s not going, it’s gone,” said one former intelligence official who worked with NATO allies. “In the eyes of the numerical majority of NATO countries, the U.K. is the only country that could replace America.”
“Trust arrives on foot but leaves on horseback,” the official added. “It will take a long time to rebuild it.”
“That doesn’t mean that NATO as an institution is dead or worthless; quite the contrary,” they said, “but the old NATO structure, which was based in trust on the U.S. coming to bail out Europe in event of a disastrous attack by the Russians, now has no credibility.”
Britain’s scramble to put together a “coalition of the willing” for Ukraine, with NATO at the heart of discussions, despite the threats from Vladimir Putin, shows that Starmer and his Defense Secretary John Healey understand its value as an institution, the former official said.
NATO’s main value lies in its creation of space, both literal and figurative, for countries to exchange intelligence and confidences, they said.
“The EU has got nothing like this at all, and NATO does it — not just with its members, but with its partners, which include Japan and Australia. NATO is actually already a global organization, it just needs to formalize it.”
The U.K. is already working to strengthen ties within NATO, leading almost weekly summits with France over Ukraine’s future and the future of Europe’s defense capabilities.
Despite Secretary of State Marco Rubio’s insistence this month that the U.S. is as “active in NATO as it has ever been,” recent moves have shown this may not always be the case — with the question remaining for a cash-strapped and unpopular Labour government: “Can Britain step up?”
