Russian forces are advancing in the northern Ukrainian region of Sumy, bringing the regional capital within range of their drones and artillery, according to Ukrainian officials and analysts.

The advance towards the city of Sumy - the administrative center of the Sumy region - comes as Kyiv showed its ability to continue fighting by conducting a series of strikes in recent days, hitting Russian strategic bombers and the Crimean Bridge.

Russian forces on Wednesday advanced further into Ukraine's northern region of Sumy, threatening the regional capital after taking more than 150 square km (58 sq miles) of the area in less than two weeks,