The US think tank, Institute for the Study of War, says Russian forces conducted a large-scale missile campaign on Friday to strike critical Ukrainian energy infrastructure and carried out one of the largest missile attacks on Kyiv to date.
Russia's defense ministry said on Saturday that it carried out a massive attack from air and from sea on Ukrainian military command systems, defense industry facilities, and related energy facilities.
A ministry spokesperson said the Ukrainian air defense system has wasted an enormous resource on decoys launched by Russian forces.
Britain's defense ministry says "the waves of strikes have largely consisted of air and maritime launched cruise missiles, but have almost certainly also included Iranian-provided uncrewed aerial vehicles being launched from Russia's Krasnodar region."
In an interview with the British newspaper, The Guardian, Ukraine's defense minister Oleksii Reznikov said a new offensive by Russia could happen by February.
He reportedly said that about half of the 300,000 mobilized reservists will have completed minimal training by then.
Ukraine's armed forces commander-in-chief, Valerii Zaluzhnyi, told another British media outlet that the Russians are preparing some 200,000 fresh troops.
He added that he has no doubt "they will have another go at Kyiv."