Ukrainian forces kept pushing north in the Kharkiv region and advancing to the south and east of the country after the swift fall of Russia’s main bastion in the northeast, Ukraine’s army chief said on Sunday.

Ukrainian President Volodymyr Zelensky hailed Russia’s retreat from the city of Izium in the Kharkiv province as a breakthrough in the six-month-old war, saying this winter could bring more rapid gains of territory if Kyiv can get more powerful weapons.