Judy Woodruff:

To explore how these investigations work and foreign policy implications, I'm joined by two men who served in both Democratic and Republican administrations.

Andrew Weiss was a staffer on the National Security Council, where he focused on Russia. He's now with the Carnegie Endowment for International Peace. And David Kris served as the Department of Justice top national security official.

And, gentlemen, we welcome you both to the "NewsHour."

I'm going to start with you, Andrew Weiss.

How unprecedented is it to have these kinds of revelations that we have seen about the president and Russian leaders?