Ukrainian soldiers fighting in east in a way that Pentagon wants to study

Despite the withdrawal from Sievierodonetsk Ukrainian forces created a level of defense that had Russian troops at a standstill as they became effective in finding and killing Russian command and control and destroying large levels of Russian materiel, US senior officials said during the briefing on Ukraine.
The 'gigantic strategic failure' on the side of the Russian forces was also discussed - repositioning soldiers out from the north around to the east to try and make some gains. "And those gains, as you've seen, have been relatively small at a gigantic cost. Ukrainians are able to go toe-to-toe," top military officials explained.