Ukraine said on Friday its troops had broken through Russia's first line of defences in several places, though they have then encountered even more heavily-fortified Russian positions.
Deputy Defence Minister Hanna Maliar said Kyiv's troops, in a much-vaunted counteroffensive against Russian forces, were advancing in the Zaporizhzhia region. Washington also said on Friday that Kyiv had made notable progress on the southern front in the last 72 hours.
"There is an offensive in several directions and in certain areas. And in some places, in certain areas, this first line was broken through. In some areas it was not broken through, the situation is different there," Maliar said on television.
She added, however, that Kyiv's troops who have been battling to advance through heavily-mined areas for almost three months had now run into major defensive Russian fortifications.
"Where we have already moved to the next line... the enemy is much more fortified there and, in addition to the mining, we also see concrete fortifications, for example, under the main commanding heights, and our armed forces have to overcome a lot of obstacles in order to move forward," she said.
In Washington, White House National Security Council spokesman John Kirby said the United States had "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".
"They have achieved some success against that second line of Russian defenses," Kirby said, adding it was up to Ukraine on how to capitalize on that 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.
Ukraine's counteroffensive has not yet recaptured any major settlements, though it has retaken more than a dozen small villages. Last week it captured the village of Robotyne, beyond which lies Russian-occupied high ground, huge anti-tank ditches and lines of concrete fortifications visible from space.
Russia already calls the Ukrainian push a failure; Kyiv says it has been advancing slowly on purpose to minimise losses, and that its task is more difficult because it lacks the air power that its Western allies take for granted.
Kyiv bristled this week over news reports quoting unidentified U.S. officials complaining about its slow progress. Some fear the West's staunch support could begin to falter as colder and wetter weather further hampers progress on the battlefield later this year.
In an interview in Kyiv on Friday, senior presidential adviser Mykhailo Podolyak told Reuters that for now any negotiations with Russia would amount to a "capitulation" for both Ukraine and the democracies that support it.
He said Ukraine's Western allies, who have poured in billions of dollars of weaponry to help the counteroffensive, understood there could be no kind of "compromise" with Moscow in the war.
"At the moment, the partners understand that this war will no longer end in a compromise solution - that is, either we destroy Russia's capabilities by military means, and to do this we need the appropriate tools, or this war with such level of aggression will continue for some time."
