KYIV — Ukraine said Monday "another massive attack" on Kyiv by Russian drones was underway, a day after the country's top military commander vowed to increase the "scale and depth" of strikes on Russia.

With diplomatic efforts between Ukraine and Russia at a halt, a new "massive" drone attack rocked Kyiv on Monday, killing at least five people and injuring about 20 more, after Ukraine said it would increase the "scale and depth" of its operations against Russian energy and military infrastructure.