Ukrainian forces have penetrated the main Russian defensive line in their country’s southeast, raising hopes of a breakthrough that would reinvigorate the slow-moving counteroffensive. Ukrainian paratroopers are fighting through entrenched Russian positions on the edge of the village of Verbove, a Ukrainian officer in the area said. Ukrainian forces have also reached the main defensive line to the south of nearby Robotyne village, he said. Ukraine’s military confirmed advances toward Verbove and south of Robotyne, without giving details. Describing the advance, the Ukrainian officer held up three fingers representing lines of attack through entrenched Russian positions on the western flank...