The most dangerous spy is not necessarily the one caught stealing secrets. It is the one who remains undetected for years, quietly betraying his country while his foreign handlers build an ever more devastating intelligence operation.

Such turncoats are among the most notorious names in intelligence history: FBI agent Robert Hanssen who spied for the Soviets and then the Russians long after the fall of the USSR; the CIA traitor Rick Ames whose betrayal led to the executions of multiple Soviet officials working secretly for the US; and – in one of the most famous British cases – the MI6 double agent Kim Philby of the Cambridge Five spy ring. 

Whatever success we have in counterintelligence is always temporary, until we find the next penetration of our government(s) and the next dangerous spy. That is the lesson from Britain’s latest espionage arrest — and one that American intelligence has also learned painfully over the decades. 

British authorities have charged 24-year-old Royal Navy serviceman Teddy Young with obtaining classified information and preparing to disclose it to Russia. Prosecutors allege he accessed sensitive defence and intelligence material and took steps toward contacting Russian authorities via the dark web. The investigation remains ongoing, and Young has not yet been convicted of any charges, despite an apparent earlier arrest in 2025. 

There is an important distinction here from earlier Russian and Soviet cases: Not every espionage case results in catastrophic damage. Sometimes counterintelligence catches a potential spy before he or she can deliver his or her secrets. 

That is precisely what professional counterintelligence services are supposed to accomplish and, from the initial reports, what the British services achieved with this case. Consider the extraordinary contrast with one of America’s most damaging espionage scandals, also of a sailor and his extended family, but one that is often overlooked in the pantheon of Soviet and Russian spy cases: the John Walker Soviet spy ring. 

In 1967, Walker, a US Navy communications specialist, walked into the Soviet Embassy in Washington and volunteered to betray his country. For the next 17 years, he supplied the KGB with extraordinarily sensitive American naval cryptographic secrets. 

The damage was staggering. The KGB gained access to information that compromised at least one million classified messages, potentially exposing American naval operations and capabilities. Worse, Walker built a network. He recruited his brother, his son, and a trusted Navy colleague, Jerry Whitworth, into the conspiracy. Over the years, it became a family enterprise in treason. 

For all their faults — and there are many (the Russians are not 10 feet tall) —the Russian services are exceptionally good at running agent operations, especially at compartmenting them. That is why Philby, Hanssen, Ames, Walker, and many other Soviet and Russian spies carried out their espionage sometimes for many years, or even decades, before they were caught or escaped to the USSR. 

During my decades in intelligence, including as a CIA operations officer and station chief, I came to appreciate how disciplined Russian intelligence services can be in protecting their human sources. 

Compartmentation is central to Russian tradecraft. Sources may know little or nothing about other agents, operational channels are separated, and handlers carefully limit who knows what. Once recruited, if the initial recruitment is protected, it becomes exceedingly difficult to find a spy. Hanssen was run for 20 years by three different Soviet and Russian services who were content not even to know his actual name. That level of patience and discipline is hard to replicate in the West. 

The Russian services use dead drops – passing on items to someone without meeting them, clandestine communications, and elaborate security measures, making it extraordinarily difficult to deconstruct an espionage network once it is established. The public should not believe that reckless FSB and GRU recruiting via Telegram and other hybrid warfare represents their very best. Instead, they reflect wartime desperation, much of it not based on tried-and-tested Russian “impersonal communications” tradecraft. 

Indeed, technology changes, and sometimes the tradecraft evolves with it. But the Russians are not inclined to change tactics that have worked for decades. They also prey on human vulnerabilities that rarely change: greed, ego, resentment, ideology, and personal grievances remain powerful recruitment opportunities. Sometimes, as Walker demonstrated, the prospective spy even approaches the Russians, or attempts to, and that is the decisive moment. 

That makes the Royal Navy serviceman being charged this week especially instructive. If the publicly reported allegations are substantiated, British authorities appear to have interrupted a potential espionage operation before it matured into another Walker-style catastrophe, as the accused was apparently attempting to contact the Russian services via the dark web or other means. We do not yet know the full extent of any compromise, or whether there was one. 

But while we wait, we should recognise the professionalism required to identify suspicious conduct, investigate it, and intervene. We should offer some well-deserved praise to MI5, Scotland Yard, and any other agencies involved. 

Counterintelligence successes rarely attract the attention accorded to failures. We hear about spies who betray secrets for decades, but less often about plots disrupted before the first classified document reaches an adversary. Those successes matter enormously. 

Today, Russia and China are conducting aggressive intelligence campaigns against the United States, Britain, and our closest Nato allies. Their methods encompass traditional human espionage alongside cyber penetration, technological theft, influence operations (active measures as the Russians call them), and increasingly sophisticated forms of hybrid warfare.

And the stakes are higher than ever as Russia wages war against Ukraine and challenges European security across the grey zone. They aim to destroy the alliance and undermine democracy worldwide. 

Countering both Russia and China requires experienced counterintelligence services, strong allied cooperation, and intelligence cultures that recognise warning signs rather than dismiss them. Other headlines out of Germany this week over the arrest of a former chief of the BND, Germany’s foreign intelligence, should give us all pause. 

Good “CI,” as we call it, requires vigilance without complacency. Because in this shadow war, success is not simply catching the traitor. It is catching him before the secrets are gone. 

Spy operations, especially when caught, also remind us of another truth. The Russians and their Chinese partners are out for world domination. Nato is the envy of the Russian Federation. And as an alliance, we can only be undone from within. As King Charles reminded us during his recent visit to the United States, the alliance has lasted 80 years and has stood — not without difficulties — the test of time. Intelligence-sharing is a key part of the alliance, and protecting those secrets is protecting its crown jewels. 

Sean Wiswesser is a former CIA Senior Operations Officer and expert on Russian Intelligence, Espionage, and Defence Issues. He is the author of Tradecraft, Tactics and Dirty Tricks: Russian Intelligence and Putin’s Secret War (Naval Institute Press, 2026). 

All statements of fact, opinion, or analysis expressed are those of the author and do not reflect the official positions or views of the US Government. Nothing in the contents should be construed as asserting or implying US Government authentication of information or endorsement of the author’s views.