A nighttime missile and drone attack on Ukraine killed at least four people and injured 20 others in Kyiv, city mayor Vitali Klitschko said Friday, as Russia targeted at least six regions across the country with 407 drones and 44 missiles in one of its largest co-ordinated attacks of the three-year war.

The attacks come days after Trump says Putin had "very strongly" promised response to Ukraine "Spider web" attack.

Russia launched drones and ballistic missiles at multiple targets across Ukraine, Kyiv authorities said on Friday, in a deadly air assault that left at least four people dead and 20 wounded in the capital.