Ukrainian forces went on the offensive in the Kursk region of Russia, Ukrainian and Russian officials said Sunday, in what appeared to be an effort to regain the initiative there as they struggle to thwart relentless Russian assaults across eastern Ukraine.

President Volodymyr Zelenskyy says he will urge allies to boost Ukraine’s air defenses at a meeting this week in Germany, while both sides said Kyiv’s forces pressed new attacks Sunday in Russia’s Kursk region.