Ukraine's Zelenskyy warns Putin will push Russia's war "very quickly" onto NATO soil if he's not stopped

Eastern Ukraine — Ukraine's President Volodymyr Zelenskyy met our CBS News team at an undisclosed, bombed-out building in the far east of his country. Bombed-out buildings aren't hard to come by here.

With spring approaching, Zelenskyy said Ukraine's forces had managed to hold off Russian advances through the worst of the winter months.

"We have stabilized the situation. It is better than it used to be two or three months ago when we had a big deficit of artillery ammunition, different kinds of weapons," he said, "We totally didn't see the big, huge counteroffensive from Russia... They didn't have success."