(Bloomberg) -- Two of the world’s biggest airline ticket-booking systems said they’re evaluating their exposure to Russian customers including Aeroflot PJSC in light of sanctions on the country after it invaded Ukraine. 

Amadeus IT Group, whose ticketing software is used by Russia’s S7 and Ural Airlines, is weighing the potential impact of measures implemented by a growing group of countries in Europe and the U.S.  

“We are constantly monitoring the situation, which is evolving rapidly,” the Spanish company said in a statement. “We continue to assess and evaluate the potential impact of international sanctions imposed by the U.K., the U.S. and the European Union on Russia and any counter-measures by Russia.”

Southlake, Texas-based Sabre Corp., which provides software for Russian flag carrier Aeroflot, said it was monitoring the situation. “We are complying and will continue to comply with sanctions imposed,” the company said, without providing details of its actions. 

EU sanctions against Russia prohibit “the sale, supply, transfer or export of all goods and technology linked to aircraft, helicopters and spacecraft,” according to Transport Commissioner Adina Valean.

Airspace bans have already severely curtailed the level of flying between Russia and other countries. Being shut out of online booking software could make it difficult for airlines in the country to continue operating domestically.  

While the EU language is sweeping, it doesn’t specifically call out airline reservation systems. The U.S. has banned Russian airlines from its airspace and, along with the EU, has imposed a number of financial sanctions making it harder to conduct business in Russia.

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