A group of Russian airlines is stripping planes of spare parts as sanctions implemented due to Moscow’s invasion of Ukraine impact the country.

Sources told Reuters on Monday that major Russian airlines such as Aeroflot have grounded their planes so they can be disassembled for spare parts, adding that airlines are taking parts from their planes to keep them airworthy.

Russian-made Sukhoi Superjets, which are dependent on assembled foreign parts, have already started the disassembly process, removing an engine from a grounded jet to allow another Superjet to continue flying.

The disused airplanes from which parts are removed to keep others flying are often referred to as “Christmas trees.”  The process is linked to financial difficulties due to widespread reshuffling from the sanctions imposed by Western powers, according to Reuters.

Sanctions on Moscow stem from its invasion of Ukraine, which began in February, and have prevented Russia from obtaining spare engine parts or undergoing maintenance checks in Western countries.

Oleg Panteleyev, the head of the Aviaport aviation think tank, told Reuters that most Western-based manufacturers know that Sukhoi Superjets fully operate in Russia.

“Western manufacturers understand that almost all Superjets are being operated in Russia,” said Panteleyev.  “You can simply stop producing and shipping spare parts – and it will hurt.”

Russian officials hope that some of the used aircraft parts will ensure that foreign-built aircrafts can continue to fly through 2025, Reuters reported.

A source also said that due to the Western-imposed sanctions, unused jets are being stripped for spare parts, as Russian jets are currently flying fewer routes than normal.

This comes as Aeroloft has experienced a 22 percent traffic fall due to the Western-imposed sanctions against Russia, according to data provided by the company.

Sources also say Middle East and Asian companies may be at risk of secondary sanctions from Western powers if they provide aircraft supplies to Russia.