The MiG-31 is one of Russia's most modern fighter jets, capable of carrying Kinzhal hypersonic missiles - which can carry both conventional and nuclear warheads.
According to the FSB, Ukrainian agents have tried to convince the Russian pilots to desert, but the ultimate goal is not just to steal goods.
Their real plan is to shoot down the MiG-31 in Romania, which would trigger an international incident with NATO, the FSB said.
The FSB alleges that the entire operation was organized by the Military Intelligence Service of Ukraine (HUR), in coordination with the British Foreign Intelligence Service (MI6).
A MiG-31 pilot said he was approached last year by a person claiming to be Sergey Lugovsky, a researcher at independent investigation agency Bellingcat. Initially, Lugovsky only asked for technical advice but then moved to offer a fee if the pilot agreed to be discharged.
After being refused, another Ukrainian spy - using the nickname Aleksandr - approached and promised to pay 3 million USD and a foreign passport for the pilot to control the plane through an air base near the city of Constanta (Romania).
According to the FSB, the plan was designed to get the NATO air defense system to react, creating an event where Kiev could blame Russia, thereby pulling the Western alliance deeper into the conflict.
Efforts to extort Russian soldiers are not new. In 2023, Russian helicopter pilot Maksim Kuzminov defected to Ukraine on a Mi 8, landing in Kiev-controlled territory with the support of HUR. Two other crew members, unknown to the plan, died upon landing.
A year later, Kuzminov was assassinated in Spain, where he lived under a new identity with a Ukrainian passport.
Previously, in 2022, FSB accused Bellingcat's former investigative reporter Christo Grozev of being involved in another failed attempt to recruit Russian pilots. Grozev denied it, saying he had just entered with Ukrainian intelligence officers to film documents and that the leaked messages were fake.
The latest incident shows that the Russia-Ukraine spiel war continues to be tense, while Moscow accuses the West of directing dangerous covert operations to incite conflict beyond Ukraines borders.