Russia lost a third of its strategic bombers as talks stalled, while Moscow’s forces made marginal front-line advances.

Ukraine’s security service released footage Wednesday of its attack on Russian war planes at multiple airbases across the country. In the span of a few hours on Sunday, nearly a third of Moscow’s strategic bomber fleet was destroyed or damaged with cheaply made drones sneaked into Russian territory, according to Ukrainian officials.

President Volodymyr Zelenskyy said Defense Minister Rustem Umerov would sit down with Russian officials at the second round of peace talks on Monday.