Foreign Minister Dmytro Kuleba told AFP last week the West was not pressuring Kyiv

 Foreign Minister Dmytro Kuleba told AFP last week the West was not pressuring Kyiv 

 post faster gains, and that Ukrainian forces would recapture all occupied territory, making clear: "we don't care how long it takes".

But reports in US media suggest that there is growing consternation in Washington over the pace of gains as well as Ukraine's battlefield strategy, fanning reservations over how long Kyiv's most staunch ally can keep up support.

And newly-reported US intelligence estimates show the staggering cost for Ukraine with some 70,000 military personnel killed and even more injured.

Russian Defence Minister Sergei Shoigu this month weighed in, claiming Ukraine's resources and offensive potential were exhausted.

Mykola Bielieskov, a research fellow at the National Institute for Strategic Studies in Kyiv, said given Russian defensive preparations and artillery firepower, the offensive was always going to be long and hard.

"I don't understand what people expected," he told AFP.

He also attributed the pace of gains to Ukraine's strategy of preserving as much manpower and hardware as possible.

"The whole idea that without fire superiority Ukraine can unhinge this Russian defence and quickly create openings -- it was misplaced," he added.

Vitali, a 21-year-old Ukrainian soldier on leave in the capital, said the military was spread too thinly along the front to launch a concentrated offensive.