Russian forces bombarded the outskirts of the capital Kyiv and the besieged city of Chernihiv in northern Ukraine on Wednesday, a day after Russia said it would scale down military operations in both cities in what the West dismissed as a ploy to regroup by invaders suffering heavy losses.

Pentagon spokesman John Kirby said some of the Russian forces may have already moved into Belarus, as opposed to their home garrisons.

"They are leaving Kyiv and heading more towards the north, away from the city," Kirby told a news conference on Wednesday.

Troops leaving the area included some of those around Chernihiv along with those fighting near the town of Sumy, Kirby said.

He said Kyiv was still being attacked by air and ground strikes.

Military analysts say Russia has reframed its war goals in Ukraine in a way that may make it easier for Moscow to claim a face-saving victory despite a woeful campaign in which his army has suffered humiliating setbacks.

Kirby said Russian contractor Wagner Group had deployed about 1000 personnel into Ukraine's Donbas region, which Moscow has declared a priority.

Russian President Vladimir Putin has said in the past that Wagner and other private groups neither represent the Russian state nor are paid by it, though he says they have a right to operate provided they do not break Russian law.

The European Union imposed sanctions on Wagner last year, accusing it of fuelling violence, looting natural resources and destabilizing countries around the world.

Earlier on Wednesday, the top U.S. military commander in Europe told Congress that President Joe Biden's administration made a policy decision to keep US warships out of the Black Sea prior to Russia's invasion of Ukraine.

The disclosure underscored the efforts that Biden took before Russia's invasion to avoid giving Moscow any US-related pretext for attacking Ukraine, something that Republican critics has seized upon in recent days as they press for a stronger US response.

Australian Associated Press