From the trenches of Russia's undeclared war on Ukraine, a warning for America about Putin's intentions

Eastern Ukraine — The trenches look like something straight out of the first world war: Ukrainian soldiers dug in only about 300 yards from Russian-backed rebel fighters. But while it looks like a war from 100 years ago, some believe the grim conflict that's been grinding on for seven years in eastern Ukraine is the front line in a new cold war brewing between Russia and the United States.

CBS News correspondent Holly Williams hitched a ride with the Ukrainian military, joined by Ukraine's President Volodymyr Zelenskyy, to a corner of Europe where lush pastures have become killing fields.