Ukraine stepped up its drive to retake Russian-controlled southern Ukraine by trying to bomb and isolate Russian troops in hard-to-resupply areas.

In a Thursday night address, President Volodymyr Zelenskyy once again signaled that Ukrainians would not be intimidated by the Russian invasion, which began on Feb. 24 and has had economic and other consequences far beyond Ukraine's borders.

"We shall do everything to ensure no one anywhere in the world remains indifferent to this terrible war that Russia has unleashed on our country and against the very notion of freedom," Zelenskyy said.