bumps and grand promises of u.s. support. on wednesday, secretary of state blinken visits kiev, but earlier this week a congressional delegation was here. >> i think vladimir putin has made the biggest mistake of his career. >> reporter: vowing more tough action in washington against russian aggression. >> we will impose crippling economic sanctions, but more important, we will give the people of ukraine the arms, lethal arms, they need to defend their lives and livelihoods. >> reporter: it certainly doesn't look deterred. these are the latest images of russia's live-fire military exercises near its border. where the latest ukrainian defense intelligence assessment obtained exclusively by cnn says russia has almost completed its military build up. the assessment says there are