Ukraine’s counter-offensive against Russian troops in the south of the country has made “notable progress” in recent days, the White House said on Friday.
Three months into the Nato-backed push, Ukrainian forces penetrated Russian lines this week, marking a significant moment in the war.
“We have noted over the last 72 hours or so, some notable progress by Ukrainian armed forces in that southern line of defence coming out of the Zaporizhzhia area,” White House National Security spokesman John Kirby said during a press call.
“And they have achieved some success against that second line of Russian defences,” Mr Kirby said.
Military experts said Ukrainian forces have advanced through several kilometres of Russian lines between Robotyne and Verbove in the Zaporizhzhia region.
Kyiv’s aim, they say, is to advance south towards the Sea of Azov and off cut Russian troops’ access to Crimea.
But the Russian army has set up a formidable defence system ahead, which includes fortified trenches, mines, tanks, sniper zones and concrete pill boxes.
“That is not to say that they aren't mindful that they still got some tough fighting ahead of them as they try to push further south,” Mr Kirby said. He added that the US would remain committed to ensuring Ukraine's readiness.
The administration of President Joe Biden has so far contributed more than $43 billion in security assistance to Ukraine since Russia's invasion began in February last year.
It has also supplied Ukrainian troops with a wide range of weapons systems, tanks, jets and training.
The development comes after media reports last week quoted unnamed US and western officials who said that Ukraine’s offensive had made limited progress in recent months.
Mr Kirby admitted that Ukraine’s progress has been “slow” in some areas, but that such comments are “not helpful” in ensuring Ukraine’s success.
“We've all seen the criticism by anonymous officials out there, which frankly is not helpful,” Mr Kirby said.
“It has been slow in some areas, slower than they themselves have said they'd like to go.
“You can't deny that they have made progress now.”