Ukrainian President Volodymyr Zelensky has said defences must be quickly beefed up across the front line, after meeting commanders in some of the main pressure points in the south and east. "In all major sectors where reinforcement is needed, [we must] speed up building of structures," he said in his nightly address. Russian forces are trying to encircle the eastern town of Avdiivka. And they are targeting the southern regions of Kherson and Zaporizhzhia. With temperatures falling below freezing and Ukraine cloaked with snow, President Zelensky has said "winter as a whole is a new phase of war".