During a 24-hour swing through Copenhagen last month, Eric Slesinger met with engineers making maritime drones, developers of war-planning software and an adviser to NATO. He had recently visited London for a dinner with a senior British intelligence official and would soon head to the Arctic to learn about the technologies that could handle extreme climates.
The packed schedule would seem more common for Mr. Slesinger in his former job as an officer at the Central Intelligence Agency. But now the 35-year-old was in high demand as he parlayed his spy agency credentials into a career as a venture capitalist focused on the suddenly relevant area of defense and national security technology in Europe.
“This is all happening at warp speed,” said Mr. Slesinger, who has backed eight defense start-ups and has negotiated with several more.
As President Trump throws the future of the trans-Atlantic relationship into question, governments across Europe have outlined plans to potentially spend hundreds of billions of euros on weapons, missile-defense programs, satellite systems and other technologies to rebuild their armies. Technologists, entrepreneurs and investors are racing to take advantage of the spending boom by creating new defense start-ups.
Few paid attention several years ago when Mr. Slesinger moved to Madrid with the idea that Europe would need to drastically increase defense spending because U.S. military protection could not be taken for granted. Now his predictions look prescient. After Mr. Trump’s inauguration, which followed his defeat of Vice President Kamala Harris in the November election, members of his administration called Europe “pathetic” and military mooches of the United States.
“Whether Trump won or Harris or anyone else, the fact would have remained that there’s a technology catch-up that needs to happen in Europe,” Mr. Slesinger said while walking between meetings in Copenhagen last month. “Maybe it’s accelerated in certain ways, but this was a long time coming.”
Mr. Slesinger is now in the unusual position of a former American intelligence officer who is trying to profit from Europe’s planned military transformation. His one-man venture capital firm, 201 Ventures, is completing a $22 million fund to invest in young start-ups at the intersection of tech and national security.
Mr. Slesinger’s initial investments include a maritime drone company in Sweden, a maker of manufacturing technology in Britain, an artificial intelligence firm in Greece and a hypersonic vehicle start-up in Germany.
The United States has a long tradition of investing in defense — Silicon Valley was started in part with Pentagon funding — and has seen the rise of several military-centric start-ups, such as Palantir and Anduril. Europe has had fewer successes, partly because defense-related businesses were viewed as so unethical that many investors there refused to put money behind them.
“There has been this awakening moment, and it’s going to result in a dramatic increase in spending in defense, security and resilience technology,” said Chris O’Connor, a partner at the NATO Innovation Fund, a 1 billion euro tech fund started with money from 24 members of the North Atlantic Treaty Organization, though not the United States.
The NATO fund is the biggest financial backer of Mr. Slesinger’s firm. Mr. O’Connor said Mr. Slesinger’s national security experience made him ideal for identifying companies with tech that could win government contracts.
“He’s going to end up playing a critical role,” Mr. O’Connor said.
Mr. Slesinger grew up just outside Washington, D.C., and attended Stanford. There, he was a standout in the mechanical engineering program, said Craig Milroy, co-director of Stanford’s Product Realization Lab, where students can workshop hardware ideas.
While many of Mr. Slesinger’s Stanford classmates explored jobs with Apple or Google, he looked elsewhere. “He came into my office one day and said, ‘I’m applying to join the C.I.A.,’” Mr. Milroy said. “That’s never happened before or since.”
Mr. Slesinger is cagey about his five and a half years working at the C.I.A. But with his engineering background, he said, he worked among more Q-like figures from the James Bond films, geeks operating in the background to solve technical problems for intelligence officers in the field.
“Imagine being a student, kind of nerd engineer, and then you get to go in this place where you have like a Santa’s workshop-like capability,” he said. “Intelligence problems are really hard, they’re gnarly, and you feel a real responsibility to do something to solve the problem.”
In 2019, Mr. Slesinger stepped back from the agency to attend Harvard Business School. He also spent a summer working for the C.I.A.’s venture capital fund, In-Q-Tel.
Around this time, he became fixated on the idea that Europe must rebuild its militaries after a generation of low investment. The United States spent about $880 billion on defense in 2024, more than double what other countries in NATO spent combined.
With the United States focused on China, Mr. Slesinger was convinced he would see the end of the so-called peace dividend, which has allowed European countries to spend more on social services and pensions since World War II, instead of on tanks and fighter jets.
Russia’s invasion of Ukraine in 2022 further crystallized his thesis. He then started the European Defense Investor Network, which now includes about 125 investors, entrepreneurs and policymakers. Last year, he started 201 Ventures.
At first, he struggled to raise funding because many investors refused to back military technologies. But he eventually raised money from NATO and found advisers including Eileen Tanghal, who used to oversee In-Q-Tel’s London office; David Ulevitch, a general partner at the Silicon Valley venture firm Andreessen Horowitz; and the author Sebastian Mallaby.
Over the past 12 months, Mr. Slesinger, who also has an Italian passport from his family’s roots there, has traveled to 15 countries. On a recent trip to the Arctic, he rode a snowmobile to a remote area being considered for testing new power sources and a communication technology. In Switzerland, he toured the world’s most powerful particle accelerator.
In February, Mr. Slesinger was in Germany for the Munich Security Conference when Vice President JD Vance delivered a blistering speech criticizing Europe. Within weeks, Germany, France, Britain and other European countries pledged to vastly increase military spending, alarmed that they could no longer count on the United States as a reliable ally.
“It felt like a sea change,” said Mr. Slesinger, who watched Mr. Vance’s speech from a laptop at a nearby hotel. “You could feel it as he was speaking.”
How much of the new spending will reach start-ups is unclear. Missiles, ammunition and fighter jets are likely to be higher priorities than tech from small, untested companies.
Mr. Slesinger said it would take years to measure success, but he expects to spend his $22 million fund in the next two years and has already begun thinking about raising a larger amount. In the past few months, he has been peppered with pitches from European entrepreneurs suddenly interested in making military tech.
For just about everyone he meets in Europe, there is one nagging question: Is he really no longer working for the C.I.A.?
“I’m really out!” he said.
