Ukraine's troops show CBS News how controversial U.S. cluster munitions help them hold Russia at bay

At a secret hide-out deep in a forest near the eastern city of Lyman, Ukrainian forces were caught in the crosshairs of a new line of Russian attack. Our CBS News team huddled in the dugout with the troops, not far from the eastern front line, where Russia was putting them under intense pressure with a barrage of artillery in a bid to stretch Ukraine's resources. 

Moscow wants to force the Ukrainians to bolster their defenses in the area by pulling soldiers away from their counteroffensive in the south. 

"We've got...