The White House has recently assessed that Ukrainian forces have made "significant progress" against Russian forces in their counteroffensive in southern Ukraine, US National Security Council spokesman Kirby said.

He noted that over the past 72 hours, Washington had observed a "noticeable advance of the Ukrainian armed forces" south of Zaporizhzhia.

Separately, Kirby responded to criticism of the counteroffensive, saying it was "unhelpful" to criticize a partner and friend trying to progress against a violent regime.