WASHINGTON (Reuters) - The United States has seen notable progress by Ukrainian forces in southern Zaporizhzhia in the last 72 hours, the White House said on Friday, adding separately that it could not confirm reports that Russian missiles were put on combat duty.
"We have noted over the last 72 hours or so some notable progress by Ukrainian armed forces ...in that southern line of advance coming out of the Zaporizhzhia area, and they have achieved some success against that second line of Russian defenses," White House National Security Council spokesman John Kirby said.
Speaking to reporters on a conference call, Kirby said it was up to Ukraine on how to capitalize on their success.
"That is not to say ...that they aren't mindful that they've still got some tough fighting ahead of them as they try to push further south" or that Russia could launch a counter effort, he added.
Kirby also said he was not in a position to confirm reports on Friday that Russia's nuclear capable Sarmat intercontinental ballistic missiles had been put on combat duty.
(Reporting by Trevor Hunnicitt and Susan Heavey; Editing by Peter Graff)