Russia has detained a suspect in the killing of the head of the army's chemical weapons division, investigators said Wednesday, a day after the general and his aide were killed in a brazen blast in Moscow claimed by Ukraine.
Igor Kirillov and his assistant were killed when an explosive device attached to a scooter went off Tuesday morning outside an apartment building in southeastern Moscow.
The Kremlin said the attack proved "the Kyiv regime does not shy away from using terrorist methods".
Kirillov, 54, was the most senior military figure assassinated in Russia since Kremlin sent troops in Ukraine nearly three years ago.
"An Uzbek citizen, born in 1995, was arrested on suspicion of having committed the attack", the Investigative Committee, which probes major crimes in Russia, said in a statement.
The detained suspect said he had been "recruited by Ukrainian special forces", it added.
The handcuffed man was shown in video footage confessing to the attack, with several cuts on his face.
He said that he was promised "$100,000 and a European passport" for carrying out the attack.
Investigators said the suspect had told them he came to Moscow to carry out the attack and received an explosive device which he placed on an electric scooter parked outside Kirillov's apartment building, which he activated via remote control.
A camera mounted on the dashboard of a rented car parked outside the building had filmed the attack and streamed it "live to the attack organisers, in the (Ukrainian) city of Dnipro".
The suspect faces a charge of carrying out a "terrorist" attack, and investigators said they were seeking to identify others involved.
Kremlin spokesman Dmitry Peskov praised security services for working "effectively" and "fast" in detaining a suspect.
The blast went off in a residential area in southeast Moscow a day after President Vladimir Putin hailed Russian troop successes in Ukraine.
Kirillov was the head of the Russian army's chemical, biological and radiological weapons unit and was recently sanctioned by Britain over the alleged use of chemical weapons in Ukraine.
- 'War criminal' -
A source in Ukraine's SBU security service told AFP on Tuesday that it was behind the explosion in what it called a "special operation", calling Kirillov a "war criminal".
The SBU had announced charges against Kirillov on Monday for the alleged use of chemical weapons in Ukraine.
Russian authorities said they were probing the attack as "terrorism".
But the SBU source told AFP: "Kirillov was a war criminal and an absolutely legitimate target, as he gave orders to use banned chemical weapons against the Ukrainian military."
"Such an inglorious end awaits all those who kill Ukrainians. Retribution for war crimes is inevitable," the source said.
Britain and the United States have accused Russia of using the toxic agent chloropicrin, a choking agent used widely in World War I, in violation of the Chemical Weapons Convention (CWC).
Russia has said it no longer possesses a military chemical arsenal.
Kirillov had regularly accused Kyiv and the West of running secret networks of bio-labs that were developing banned chemical agents across Ukraine -- claims rejected by the West and independent fact-checking organisations.
On Tuesday a spokesman for British Prime Minister Keir Starmer said London was "not going to mourn" Kirillov, because he "imposed suffering and death on the Ukrainian people".
Britain had slapped sanctions on Kirillov in October over alleged chemical weapons use in Ukraine.
A US official said Tuesday on condition of anonymity that Washington "was not aware of the operation in advance and we do not support or enable these kind of activities".
Russian foreign ministry spokeswoman Maria Zakharova accused Ukraine's allies of being "accomplices" in "war crimes" by remaining silent on such killings or expressing support.
There have been assassinations on Russian territory before but such attacks in Moscow -- where fighting in Ukraine often feels distant -- are rare.
Previous targets included nationalist writer Darya Dugina -- killed in a car bomb attack outside Moscow in 2022 -- and pro-conflict military correspondent Maxim Fomin, who was blown up in a Saint Petersburg cafe in 2023.