The Russian Investigative Committee has launched a probe into involvement of Ukraine and its Western backers in terrorist activities on the country's soil.
The law enforcement body announced on Monday that it was moving forward with the procedural investigation.
A complaint filed by lawmakers last week was deemed credible enough for a formal inquiry.
The initial complaint identified the US and its allies as the driving force in a string of attacks on Russian soil.
The agency is looking into the “organization, financing and conduct of terrorist acts” by those states.
Nikolay Kharitonov of the Communist Party, one of the MPs who filed the complaint, insisted that Western countries “benefited” from the recent terrorist attack on the Crocus City Hall outside Moscow.
He argued that the geopolitical opponents of Russia stood to gain from the tragedy on Russian soil, and counted “on their inaccessibility and impunity.”
In the most recent terrorist attack, four gunmen burst into Moscow’s Crocus City Hall on March 22 and began shooting at the people who attended an event.
At least 140 people were killed in the terrorist attack, the worst in Russia’s history since the early 2000s. Some 200 people were also injured.
The chief of the Russian internal intelligence (FSB), Alexander Bortnikov, has suggested that not only Ukraine, but also the US and Britain – Kiev’s main backers in the war – may have been behind the shooting.
He said the information on the matter was general, but that investigators already have “concrete results.”
Russian President Vladimir Putin says the attackers were caught fleeing “towards Ukraine where, according to preliminary data, a window to cross the border was prepared.”
Eleven people, including the assailants, have been detained in connection with the attack and face terrorism charges.
The complaint was also signed by three Russian lawmakers as well as some public figures, including the philosopher Aleksandr Dugin.
His daughter Darya was killed by a car bomb in August 2022 in what is widely believed to have been a targeted assassination attempt aimed at her father, a prominent nationalist.
Russian investigators accused Kiev of organizing the bomb attack.
Russia says the Ukrainian government has publicly claimed credit for some of the attacks against Russian targets, such as the bombings of the Crimean Bridge.
Last week, Vasily Malyuk, who heads the Security Service of Ukraine (SBU), said his agency was behind several high-profile assassinations inside Russia.
Malyuk is among the senior Ukrainian officials wanted for terrorism by Moscow. A Moscow Court issued an arrest warrant for Malyuk on Tuesday.
The top Ukrainian security official stands accused of masterminding an attack on the Crimean Bridge connecting Russia and the Crimean Peninsula in October 2022.
Malyuk claimed responsibility for the incident in August 2023, saying he had “personally” planned the operation.
The FSB initially identified Ukraine’s military intelligence chief Kirill Budanov as the mastermind of the attack on the Crimean Bridge. The attack set fire to seven oil tankers, sparking a massive blaze and killing three people.
Crimea has repeatedly been targeted by Ukrainian drone attacks since Moscow launched its military operation in February 2022.
Russia launched the campaign in part to counter NATO’s further eastward expansion and to stop Kiev’s persecution of the pro-Russian population in eastern Ukraine.
The Kremlin says the West and NATO are playing a direct role in the Ukraine conflict by pouring advanced weapons and military equipment into the country, warning that NATO weapons are “legitimate targets” for its armed forces.