Ukrainian drone strikes on southern Russia killed a 9-year-old boy and set fire to a major oil terminal, officials said Saturday, the day after Moscow launched a massive aerial attack on its neighbor that Ukrainian President Volodymyr Zelenskyy said was one of the heaviest bombardments of the country’s energy sector in the nearly three-year war.

Russia launched a new widespread attack on Ukraine’s energy infrastructure overnight, forcing the country to implement emergency power outages, Ukrainian authorities said on Friday.

Military analysts had speculated that Moscow could escalate such attacks as a show of force after the fall of President Bashar al-Assad of Syria, its ally.

Ukraine's President Volodymyr Zelenskiy said on Saturday that Moscow had started involving "a noticeable number" of North Korean troops in its efforts to drive Ukrainian troops out of Russia's Kursk region.

Ukraine has accused Russia of deploying North Korean soldiers to the front lines in Kursk, marking a significant escalation in conflict