Ukraine said it struck a Russian air base on Saturday, while Russia continued to attack Ukraine with hundreds of drones overnight as part of a stepped-up bombing campaign that has dashed hopes for a breakthrough in efforts to end the more than 3-year-old war.

Hundreds of flights were delayed or canceled due to Ukrainian drone strikes on Saturday and overnight, according to Russia’s Transport Ministry.

The Ukrainian attacks came just days after Russia pummelled Kyiv with waves of drones and missiles overnight into Friday, in what Ukrainian officials called the largest such strike since Moscow’s all-