Russian forces are attacking cities in the Kharkiv region of eastern Ukraine in addition to key areas of the frontline. Ukrainian intelligence officials reportedly say Russia may be "softening the battlefield" before a bigger offensive in late May or June.

A US think tank, the Institute for the Study of War, said on Saturday, "Russian forces will likely make significant tactical gains in the coming weeks as Ukraine waits for US security assistance to arrive at the front" but remain unlikely to overwhelm Ukrainian defenses due to old equipment and poorly trained soldiers.

It also says, "Ukraine is very likely to stabilize the frontlines in the coming months and may be able to begin limited counteroffensive operations in late 2024 or early 2025."

The administration of US President Joe Biden recently announced additional military aid for Ukraine.

Ukrainian forces say Russia launched drone attacks on the southern region of Mykolaiv early on Sunday morning, causing no injuries but damaging a hotel building and an infrastructure facility.

Britain's Financial Times reported on Friday that Ukraine's intelligence authorities have described Russia's current attacks as "softening the battlefield" before a new large-scale offensive in late May or June.