The counteroffensive has been completely stymied. From Scott Ritter at sputnikglobe.com:

© Photo : Screenshot / Russian Defense Ministry
There has been a vigorous debate over the course of the past weeks and months about the failure of the US and NATO to provide Ukraine with modern fighter aircraft such as the F-16.
Valery Zaluzhny, the commander-in-chief of Ukraine’s armed forces, has lambasted the failure of the west to provide aircraft while at the same time pushing Ukraine to conduct a large-scale counteroffensive that no NATO country would dare attempt without possessing air superiority over the enemy.
“A very limited number would be enough,” Zaluzhny said, indicating that if the west wanted Ukraine to succeed, then delivery of the F-16 fighters needed to happen soon.
Not so fast, says the Chairman of the Joint Chiefs of Staff, General Mark Milley.
“The casualties that the Ukrainians are suffering on this offensive are not so much from Russian airpower,” Milley observed. “They’re from minefields—minefields that are covered with direct fire from anti-tank hunter-killer teams, that sort of thing.”