The Kremlin has never been afraid to assassinate its political opponents. In 1940, a Soviet agent murdered Leon Trotsky with an ice pick in Mexico City. In the 1950s, KGB agents poisoned the Ukrainian nationalist leaders Stepan Bandera and Lev Rebet in Munich. In 1978, Georgi Markov, a Bulgarian émigré broadcaster, was killed, supposedly by a poisoned pellet fired from an umbrella, on Waterloo Bridge in central London. New archival research suggests that the Soviet KGB ordered his murder.

Under President Vladimir Putin, the Russian state has continued in the same vein. Putin’s time in office began with a bloodbath. In 1999, a wave of apartment-block bombings killed more than 300 people in three Russian cities. The government blamed the attacks on Chechen terrorists, providing a pretext for a war in the breakaway republic and boosting Putin’s reputation as a tough leader. But from the start, critics poked holes in the official version of events.

The most prominent among those critics have paid a heavy price. In 2003, the investigative journalist Yuri Shchekochikhin died of a mysterious illness and the liberal politician Sergei Yushenkov was shot dead. They had both been investigating allegations that the Russian state security service, the FSB, had orchestrated the bombings to increase support for Putin and the war.

Meanwhile, many St. Petersburg liberals, who knew that Putin, while working in the city’s municipal administration, had been deeply involved in corrupt import-export, property, and licensing deals, also had unusually poor life expectancies. The liberal lawmaker Galina Starovoitova was shot in November 1998. Anatoly Sobchak, the city’s former mayor, died unexpectedly just after his onetime subordinate became president.

Living abroad offers little protection. The Chechen émigré leader Zelimkhan Yandarbiyev was blown up in Qatar in 2004. The perpetrators—two Russian military intelligence officers—were caught, released after some diplomatic arm-twisting, and returned to Russia, where they received heroes’ welcomes. Russian law explicitly permits the assassination of “extremists”—and the definition of an extremist is whatever the Kremlin wishes it to be.

In some cases, few would quibble with the designation. Musa Atayev, a Chechen field commander living in Turkey under a false name, was killed in Istanbul in February 2009. Chechen separatists have fought two wars with Russia; they have perpetrated real terrorist outrages in addition to the phony ones Russia has tried to pin on them. Their leaders, many would argue, are fair game, wherever they are in the world. The Kremlin notes that the United States also kills terrorists abroad—even U.S. citizens—with drone strikes.

But Alexander Litvinenko, whose murder by radiation poisoning in November 2006 was “probably” approved by Putin, according to a British public inquiry that published its report last week, did not fall into that category. Admittedly, he was an associate of the London-based Chechen leader Akhmed Zakayev, whom Russia has long tried to extradite (although Zakayev forswears violence and wants a negotiated settlement to the conflict).

Russian MP Andrei Lugovoi, whom the British government is seeking to extradite for his role in Litvinenko's death, in Moscow, March 2013. Maxim Shemetov / Reuters

But Litvinenko’s real crime, in the eyes of the Kremlin, was treachery, not terrorism. He was a former officer in the FSB who had fled to the United Kingdom in 2000 and obtained British citizenship in 2006. He ran a vitriolic campaign against the Putin regime, highlighting the apartment-block bombings (about which he wrote several books) and the overlap between organized crime and the Russian leadership. Most sensationally, he claimed that Putin was a pedophile. He was also working closely with another figure hated in the Kremlin, the oligarch Boris Berezovsky, who had fled Moscow after falling out with Putin. Berezovsky himself was the subject of an assassination attempt that the British authorities foiled in 2007 and then tried to play down to avoid a diplomatic confrontation with Russia.

What is not known—at least in public—is whether Russia also knew Litvinenko’s big secret: his work for the Secret Intelligence Service, Britain’s foreign espionage agency, commonly known as MI6. MI6 was conducting an extensive investigation into Russian organized crime in Spain.

LIVE AND LET DIE

The Spanish authorities began their investigation—later code-named Operation Vespa—shortly after Putin came to power. They initially tried to engage the help of the FSB—assuming, wrongly, that it would share their goal of dealing with Russian gangsterdom. But the Spanish soon concluded that the information they were passing to the FSB was ending up with the gangsters. At this point, the Spanish turned to the British for expert help. Although Litvinenko was not on the staff of MI6, he was already known to them (defectors from the FSB are rare), and they hired him as a consultant, on a monthly stipend of 2000 pounds, or around $2800. The investigation soon concluded that Russian organized crime was operating in Spain in close cooperation with the Russian state.

Marina Litvinenko, (R) widow of murdered ex-KGB agent Alexander Litvinenko, holds a copy of The Litvinenko Inquiry Report with her son Anatoly (L) in London, January 2016. Toby Melville / Reuters

It is possible that Putin ordered Litvinenko’s death without knowing that he was working on this investigation. But the murders do not stop there. Another British intelligence officer, Gareth Williams, was a codebreaker working on assignment with MI6, investigating high-level Russian government links with international narcotics trafficking. In August 2010, his decomposing body was found, folded in a duffel bag, in the bathtub of the MI6 safe house in London where he was living. The investigation into his death has led nowhere.

Alexander Perepilichny, a whistleblower who was working on the case of Sergei Magnitsky, a Russian accountant who died in prison while investigating a huge money-laundering scam involving corrupt senior officials, was found dead near his Surrey home in 2012. Belatedly, an investigation found that he had traces of a rare poison in his stomach.

All three cases bear the fingerprints of Russian involvement. And in all three cases, the British authorities have been reluctant to admit what is going on and to take the necessary steps to address it.

It should not be a great surprise that Russia uses assassination against its enemies, and that it does so expertly and ruthlessly. But for the United Kingdom to acknowledge publicly that Russian hit men are operating with impunity would be a devastating admission: that the British authorities cannot keep their own people safe.

The high end of the London real estate market is buoyed by Russian cash.

Such an admission would necessitate a full breach of diplomatic ties with Russia. It would require not only withdrawing the British ambassador but treating Russia like an enemy country: a rogue state, along the lines of North Korea or Saddam Hussein’s Iraq.

The United Kingdom is not ready for that. Its biggest energy company, BP, has a lucrative cross-shareholding arrangement with Rosneft, the Russian oil and gas company that is closest to the Kremlin. The City of London provides what are euphemistically known as “financial services” to rich Russians, offering them respectability and safety for their money. The high end of the London real estate market, in particular, is buoyed by Russian cash—often accepted with the flimsiest of precautions.

Too many people benefit from these arrangements to want them to change. Instead, the British government cites realpolitik as a reason for maintaining relations with the Kremlin. Russia—supposedly—is an essential partner in the Syrian peace talks. It would be folly to jeopardize a solution to the biggest problem on Europe’s doorstep in order to make a gesture about a murder that happened nine years ago. “Nothing we can do now can bring Litvinenko back to life,” a British official said while briefing journalists last week.

In all likelihood, British business with Russia will continue largely as normal. Efforts to hunt down Russian dirty money, to deal with organized crime, to counter propaganda, and to boost the security of the frontline states (Poland in particular) are being stepped up. But none of that is likely to do more than mildly inconvenience the regime in Russia. The real result of the Litvinenko affair is fear. Critics of the Kremlin living in London now know that they can be killed at will—and that if they are, their own government will turn a blind eye.