The scooter wouldn’t seem out of place parked outside an apartment block in Moscow, where electronic two-wheelers are a regular mode of transportation for many of the Russian capital’s 13 million residents.

But this one – a key element of a sophisticated and deadly operation – carried something other than a rider: an explosive device containing between 100 and 300 grams of TNT, according to investigators in Russia.

The bomb was planted near the building on Ryazansky Prospekt in Moscow by an undercover operative under orders from Ukraine’s disorganized state security service, the SBU, said people familiar with the attack.

A hidden camera recorded what happened next. The bomb was detonated before dawn as Lieutenant General Igor Kirillov, the head of Russia’s radioactive, chemical and biological defense forces, exited the building with his aide. The explosion killed two men.

The killing marks the latest strike in a growing shadow WAR between Kyiv and Moscow, enforced by their large and powerful state intelligence agencies, both successors to the Soviet Union’s spy agencies, with the SBU a direct descendant of the KGB.

Operating behind enemy lines, these agencies target military officials and politicians, sabotage energy infrastructure and rail systems, and use hybrid warfare tactics including cyber attacks and disinformation campaigns to sow chaos within each other’s borders.

On the Ukrainian side, the ever-controversial SBU, which the US and other Kyiv allies have long urged to reform, is fueled by internal competition with the military intelligence directorate known as GUR. Became an intelligence officer involved in the planning of operations called “liquidator of the Russians”.

An SBU official confirmed that his agency was responsible for Kirillov’s death, calling him a “war criminal” who “gave orders to use illegal chemical weapons against the Ukrainian military”. He warned: “Such a shameful end awaits all those who kill Ukrainians.”

SBU is mostly focused on domestic, but since Russia invaded Ukraine in 2014 it operates within Kremlin-controlled Ukraine and within Russia. Since Moscow’s full-scale invasion in 2022, it has attacked Russia’s Crimean bridgehead and destroyed most of its Black Sea fleet with naval drones.

The intelligence official noted several killings of pro-Russia separatist leaders in the Moscow-controlled regions of Donetsk and Luhansk between 2014 and 2021 carried out by Kyiv agents.

Another intelligence official, who spoke on condition of anonymity, said the SBU’s own agents operate within Russia’s borders, but it also recruits anti-Kremlin Russians to carry out sabotage. and even murders. The FSB SAYS on Wednesday it arrested an Uzbek suspect in Kirillov’s murder.

The SBU became an important instrument for Kyiv as it fought Russia on many fronts. Russia is struggling to counter its efforts, said Andrei Soldatov, a senior fellow at the Center for European Policy Analysis. “The FSB (Russia’s main security agency) is very good at investigating what’s already happened, but not so good at gathering intelligence about what’s coming. It’s a different skill set, he said.

“For that, the agency needs to be a very good intelligence gathering agency, meaning there is trust, good information sharing – something you don’t see in Russian agencies.”

Valentyn Nalyvaichenko, an MP who served twice as SBU chief, said the spy agency had “collected a lot of information and counterintelligence data” on Russia’s military and intelligence leadership. It found ways to plant moles, crack communications inside enemy territory, and identify vulnerabilities in Moscow’s intelligence network.

Part of the SBU’s effectiveness comes from its sheer size, ironically a result of its Soviet heritage. When Ukraine gained independence in 1991, the SBU inherited many of the KGB’s structures, resources and responsibilities, and it did not shrink.

With more than 30,000 employees and even more off-the-book operatives, the SBU is almost as big as the FBI, which has 35,000 agents. This is more than seven times the size of the UK’s domestic security service MI5, and more than four times the size of Israel’s Mossad.

“One of the key tasks of the Security Service of Ukraine, especially during the war, is to fight the special services of the enemy,” said Vasyl Malyuk, head of the SBU, in unpublished responses to the a question sent to the Financial Times earlier this year.

Malyuk declined to comment directly on operations inside Russia. But he said: “The position of the security service is clear and unambiguous: every crime of the aggressor must be punished.”

The SBU rarely takes clear public credit for the killings. Instead, it usually opts for plausible deniability.

In August 2022, the agency planted a bomb in a car belonging to Russian ultranationalist ideologue Alexander Dugin, a close ally of Russian President Vladimir Putin and proponent of the war in Ukraine. But Dugin didn’t drive; his daughter Darya Dugina was behind the wheel and died when it exploded.

The work of the SBU has always been controversial. It creates a fake murder of a dissident Russian journalist in Kyiv to allegedly expose a group of hitmen hired by Moscow to destroy Ukraine; participated in the surveillance of investigative journalists and activists who reported on alleged corruption within its ranks; and faced several embezzlement scandals.

“(The SBU) has enormous power – some would say too much power,” a western diplomat told the FT.

The diplomat said the agency over the years has proven too resistant to major reforms, despite urging from Ukraine’s biggest backer, the US, other G7 members, and other countries. in the EU.

But in the midst of war with Russia, those western countries put aside some grievances and strengthened ties and intelligence sharing. The agency has developed particularly close ties with the CIA, which has invested millions of dollars in training programs for Ukrainian agents.

“What we started in 2014 is working now,” said Nalyvaichenko about its collaboration with western agencies.

The SBU has come a long way since late February 2014, when it was dismantled by former president Viktor Yanukovych after the Euromaidan revolution. Before escaping, Yanukovych ordered a raid on the agency, with his operatives stealing important state secrets and burning what they couldn’t get by car and helicopter.

The SBU, already struggling with confidence problems, suffered major setbacks in the spring and summer of that year, as Russia annexed Crimea and seized control of cities in eastern Ukraine.

As the new director of the SBU at the time, Nalyvaichenko inherited a fractured agency full of spies loyal to the Kremlin. Thousands of agents are suspected of collaboration. A purge followed, with the authorities arresting many of their own spies and launching treason investigations.

“We started from ground zero, from the burnt operational files in our back at the SBU,” he said.

Nalyvaichenko said Kyiv is bringing in younger, patriotic agents whose allegiance is to the territory within Ukraine’s internationally recognized 1991 borders.

Since the full-scale invasion of Russia began nearly three years ago, hardly a month has gone by without a headline about a Russian official involved in its war effort being eliminated by SBU operatives.

Last month, the SBU claimed credit for killing Valery Trankovsky, the chief of staff of the 41st Missile Brigade of the Russian navy’s Black Sea fleet, in a car bombing in occupied Crimea.

But there are times when credit goes to its sister agency, the directorate of military intelligence known as GUR. Under the watchful eye of its enigmatic chief Kyrylo Budanov, the unit also conducts covert operations and assassinations beyond enemy lines.

The two agencies compete for bragging rights, each trying to outdo the other by killing higher-ranking officers or attacking larger military targets deeper and deeper. inside Russia. Sometimes they work together.

Not for the first time, the work of the SBU has weakened the Russian defense establishment. Yuri Kotenok, a Russian war correspondent, wrote that the Ukrainian secret services “feel that they have complete impunity in Russia”. He added: “Obviously no one doubts the role of Kyiv, but the fact that the enemy is all but openly boasting about it is quite symptomatic.”