At the end of the day, it is what Donald Trump does or doesn't do as crises come up and as he tries to advance his agenda. He can hurt it on the margins by this kind of talk. That's my view. He could help it with a different approach to our allies and friends and our foes.

At the end of the day, it is what Donald Trump does or doesn't do as crises come up and as he tries to advance his agenda. He can hurt it on the margins by this kind of talk. That's my view. He could help it with a different approach to our allies and friends and our foes.

The NATO alliance is not just a transactional relationship, once again. That alliance serves our interests. That alliance has been critical to keeping security in Europe, so that we do not face another world war.

Presidents always - not always, but often have bad conversations with counterparts. They just don't go out and embarrass their counterpart by talking about it. They find other ways to work it out.

There are real issues that the president Donald Trump and particularly Steve Bannon, his political adviser, are pushing. It's a vision, a rather dark vision, of a 19th century world where great powers do transactional issues.

NATO is in our national security interests. And, yes, we pay a lot for it, but, when we had Afghanistan, NATO troops were by our side from almost all of the NATO members. And they put their life and treasure on the line for us.

I know that presidents often have really bad phone conversations. What they usually don't do is go out and talk about it. That gets to my point about doing some damage on the periphery of our core policies.