One of Russia’s most powerful men, Foreign Minister Sergey Lavrov, is set to visit North Korea this weekend, in a sign of deepening relations between Moscow and Pyongyang as North Korea gets pulled deeper into Russia’s war in Ukraine.

The foreign minister’s visit is the latest high-level meeting between the two nations amid a marked upgrading of their strategic cooperation.

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.

The night was punctuated with the chilling whine of approaching drones that slammed into residential areas, exploded and sent balls of orange flames into the dark during the 10-hour barrage.