Russia's Federal Security Service (FSB) on Friday said it detained four women allegedly linked to Ukrainian intelligence who were planning attacks against senior military officials and energy infrastructure, state news agency TASS reported.
The arrests took place in Sevastopol, Voronezh, and Rostov-on-Don, the agency said in a statement.
The suspects had been recruited by Ukrainian intelligence and trained in handling firearms, explosives, drone operations, and counter-surveillance techniques, the FSB said.
The security service said searches at the suspects' residences resulted in the seizure of a significant amount of explosives, detonators, and manuals for making improvised explosive devices. Communication equipment allegedly used to contact Ukrainian handlers was also confiscated.
Criminal cases were opened against the suspects under charges related to terrorism, the FSB said, adding that they provided confessions and could face up to 30 years in prison.
Authorities are continuing investigations to identify and prosecute individuals who allegedly assisted the suspects, the statement said.