Western countries have announced sanctions targeting Russian airlines and state-affiliated media.

Boeing has suspended parts, maintenance and support for Russian airlines as well as major operations in Moscow after Russia's invasion of Ukraine.

"As the conflict continues, our teams are focused on ensuring the safety of our teammates in the region," a Boeing spokesperson said on March 1, according to Reuters.

The announcement reportedly came a day after Boeing said it had paused operations at its Moscow Training Campus and temporarily closed its office in Kiev.

Media reports say Russian airlines face the risk of jetliner groundings as sanctions imposed over the Ukraine invasion threaten their ability to fund rented planes and leasing firms look at enforcing default measures.

Some media outlets, citing IBA Group, which advises airlines, planemakers, banks and lessors, say more than half of the active commercial aircraft based in Russia are leased, mostly from foreign companies.

Reuters, in particular, says that according to analytics firm Cirium, Russian airlines have 980 passenger jets in service, of which 777 are leased.

Of these, two-thirds, or 515 jets, with an estimated market value of about US$10 billion, are rented from foreign firms.

Data from IBA reportedly shows that 713 leased Russian aircraft are registered in Bermuda and a further 34 in Ireland.  Of the 158 registered in Russia itself, a further 11 are owned by foreign banks or lessors, with the rest owned by Russian institutions.

Bloomberg says EU sanctions announced on February 27 ban the supply of “all goods and technology” linked to aircraft.  Planes can’t be insured, either.  That reportedly means that leasing firms will be required to terminate all contracts with Russian airlines over the next 30 days.  

Dublin-based AerCap, the world's biggest aircraft leasing company, says that by net book value, 5% of its fleet was leased in Russia as of Dec. 31. The company, which recently strengthened its leadership of the specialist aviation leasing industry by buying rival GECAS, has the largest exposure to Russia and Ukraine with 152 planes, according to Reuters. 

Bloomberg says that after Aercap, SMBC Aviation Capital, the Dublin-based leasing arm of Japan’s Sumitomo Mitsui Financial Group, ranks next by value among foreign lessors, with Singapore-based BOC Aviation Ltd. and Air Lease Corp. of Los Angeles holding smaller positions.

The sanctions will affect most of BOC Aviation’s aircraft in Russia.  The company reportedly said its policy is to comply with all laws applicable to its business.  It has 18 aircraft leased to four Russian carriers -- Aeroflot, Ural, S7 and AirBridgeCargo.  Another aircraft is on lease to Rossiya Airlines.

Russian state leasing firm GTLK reportedly ranks second overall with a blend of commercial jets and helicopters including the Russian-built Sukhoi Superjet 100 regional airliner, which would likely be unaffected.

Lessors reportedly might have grounds for seizing jets regardless of sanctions or ability pay, if they view themselves as compromised by the developing situation or deem aircraft to be at risk now or in the future.

Plane-rental contracts generally contain a “material adverse change” clause and leasing firms could argue that airspace closures and sanctions imposed on Russian carriers amount to just such a breach. That would allow them to declare default and seize back their aircraft, IBA President Phil Seymour said, according to Bloomberg.