Russian airlines will lease planes from foreign firms.

Russian president Vladimir Putin signed a law on Monday allowing foreign planes leased by Russian airlines to be registered as the airline's property.

The move is likely to stoke fears of a mass default involving hundreds of jetliners.

The aircraft value leased to Russian airlines is estimated to be tens of billions of dollars.

Irish-owned aircraft leased to Russian airlines alone is estimated to be between 3.5 billion and 4.5 billion, making the Irish industry one of the worst affected by the crisis.

Dublin-based AerCap has more exposure to the new law than any other company, with over 200 planes that are flying, parked or stored in Russia or Ukraine.

We are in a new place. We don't know if they will see these aircraft again, said Helane Becker, an aviation analyst.

When this is over, everything gets sorted out, as Russian carriers use up whatever parts they have and start cannibalising them.

The EU banned the sale or lease of planes to Russia as punishment for the invasion of Ukraine. Current contracts in Russia must be ended by March 28.

Even if Russia wanted to make payments on their leased planes, it would be difficult because they are out of the banking system.

The expected wave of insurance claims from lessors will lead to a decade-long court battle between insurers and lessors as to whether or not war-risk insurance will pay out.