KYIV, Ukraine -- Russia launched a second major drone and missile bombardment of Ukraine in four days, officials said Tuesday, aiming again at the power grid and apparently snubbing U.S.-led peace efforts as the war approaches the four-year mark.

As Russia’s invasion of Ukraine approaches its fifth year, the character of the war continues to evolve into a technical struggle shaped by drones, electronic warfare, and the ability to strike at depth.

Sgt. Dimko Zhluktenko, a commander of a drone team, told Business Insider what it was like flying in the heavy fog that Russia used to its advantage.

Over the past day, Russian forces attacked two districts of the Chernihiv region with drones, damaging residential buildings as well as windows in a lyceum, a local administrative office, a kindergarten,

In Kharkiv, ​30 km (18 miles) from the border and also a frequent Russian target, Regional Governor Oleh Syniehubov said one person had died in a strike on the outskirts of the city. Syniehubov said three ​people were injured.