White House national security adviser Jake Sullivan told a news conference that the US president "has decided that he will not supply (Kiev) Atacams missiles, but has not ruled out this possibility in the future."

Ukrainian President Volodymyr Zelensky, who is in Washington on Thursday for a visit to the White House, said this week that leaving without such powerful tactical missiles would be a "disappointment" for him.

He praised the results of the counteroffensive by Ukraine's armed forces and was criticized by unnamed U.S. military officials in the press.

"Ukraine is already regaining its territory, and it is doing it systematically, step by step," he said.

Joe Biden's adviser said that thanks to US military assistance in particular, Ukrainian forces succeeded "in liberating territory in 3 months that exceeds what the Russians were able to seize in 8 months."

"Many major cities in Ukraine are not under Russian occupation or control today. First thanks to the courage of the Ukrainian soldiers and the Ukrainian people who support them, but also, and to a large extent, thanks to the material support we have provided."

Some Republican members of Congress are calling on the United States to end financial and military aid to Ukraine, saying its cause is lost.