Zelensky: Ukrainian army 'knows how to surprise'

President Volodymyr Zelensky praised the Ukrainian army on Thursday for its ability "to surprise" and achieve results, making no direct reference to the situation in a Russian region where Moscow says Kyiv has launched a cross-border assault.

The Ukrainian military appears to have adopted a strategy of strict silence for now on activity in Russia's Kursk region, where Moscow said Kyiv's military has been operating since Tuesday.

"Everyone can see that the Ukrainian army knows how to surprise. And knows how to achieve results," Zelensky said at an event to unveil a new digital app to cut paperwork for the military.

"This is demonstrated by the battlefield, where our soldiers not only withstood the overwhelming force of the occupiers, but also are destroying it in the way necessary to protect Ukraine - our state and independence", he said in a video from the presentation posted on Telegram messenger.