By Pavel Polityuk KYIV (Reuters) -Ukrainian and Russian troops battled in eastern regions on Thursday as Kyiv tried to push back occupying forces, while President Volodymyr Zelenskiy urged the West to provide his army with heavy tanks to boost their firepower. The Ukrainian military said the Russians were focused on an offensive in the Bakhmut sector of the Donetsk region, but their attacks in the Avdiivka and Kupiansk sectors were unsuccessful. The governor of neighbouring Luhansk region, meanwhile, said Ukrainian troops were recapturing areas there “step-by-step” but cautioned it was “not ha…