The reservation system that is the backbone of airlines around the world has terminated its agreement with Russian government-owned carrier Aeroflot, crippling its ability to sell seats.
source https://www.cnn.com/travel/article/russian-airline-aeroflot-sabre-reservations/index.html
source https://www.cnn.com/travel/article/russian-airline-aeroflot-sabre-reservations/index.html