"Things are very difficult in Donetsk region - fierce battles," Zelenskiy said in his nightly video address. "But however difficult it is and however much pressure there is, we must endure ... We have no alternative to defending ourselves and winning."

Russia, he said, was applying increased pressure to "make up for its defeats last year. We see that on various sectors of the front and also pressure in terms of information."

(Reporting by Ron Popeski and Nick Starkov; editing by Grant McCool)