Crunch time

Tough-minded, Vidia reacted in much the same way as he had in Uganda. Whenever he met Indians in Kenya, he challenged them, demanding to know their backup plans in case of trouble. He called it "crunch time." "Very well then," he [V. S. Naipaul] would say after the first pleasantries, "what are you going to do when crunch time comes?

Source: wiktionary

His decision on cluster munitions, which drew scorn from progressives in Congress, is indicative of a sense in Washington that the war is reaching crunch time as Ukraine wages a slow but steady counter-offensive.

Source: wiktionary