Concern about risk of increasing civilian casualtiespublished at 18:24 Greenwich Mean Time 28 February 2022
Jonathan Beale
BBC defence correspondent
Western officials say the Russian military has made errors and has faced challenges to their invasion of Ukraine. They say Russia has underestimated the will of the Ukrainian forces to fight and their capabilities.
Officials point to problems faced by Russian forces to resupply some units and to get engineering support such as bridging to forward units.
This, they say, has been exacerbated by Russia's failure to destroy Ukraine's air defence systems.
Ukranian forces have dispersed and have been able to ambush Russian forces and concentrate on defending urban areas where Russian forces will find it hard to manoeuvre, Western officials said.
However, they expressed concern about the increase in use of Russian artillery fire - including in Kiev and Kharkiv and the subsequent risks of indiscriminate fire and increasing civilian casualties.