Russian troops were keeping up pressure on Ukraine’s capital and air raid sirens were heard across the besieged country overnight as Russian forces kept up their onslaught on Ukraine. Meanwhile, talks resumed between the two sides on Monday but prospects for a speedy end to the fighting appeared dim. Russia escalated its offensive on Sunday by shelling areas close to the Polish border, including an air base critical to Ukraine’s defense. The fighting, now in its third week, continued to exact a human toll. The war has forced more than 2.8 million people to flee Ukraine. Thousands of civilians and soldiers have been killed.