CNN —Weeks into Ukraine’s highly anticipated counteroffensive, Western officials describe increasingly “sobering” assessments about Ukrainian forces’ ability to retake significant territory, four senior US and western officials briefed on the latest intelligence told CNN. But for them to really make progress that would change the balance of this conflict, I think, it’s extremely, highly unlikely,” a senior western diplomat told CNN. Ukrainian forces have incurred staggering losses there, leading Ukrainian commanders to hold back some units to regroup and reduce casualties. “Russians have a number of defensive lines and they [Ukrainian forces] haven’t really gone through the first line,” said a senior Western diplomat. “The problem, of course, here is the prospect of the blame game that the Ukrainians would then blame it on us,” said a senior western diplomat.