I personally found Donald Trump's praise for Vladimir Putin troubling or even chilling, frankly. In a room full of military veterans, to be effusing about his great leadership and how strong he is and how popular he is, while disrespecting the American president and American generals, I don't know. That was, I think, not just troubling to me, but to a lot of listeners and I think, frankly, to a lot of Republican listeners as well.

We got the Iran sanctions done. We got an agreement by Russia to allow us to use Afghanistan to transit supplies for our forces. We got a Security Council resolution on Libya. We got Russia into the WTO to bring in to it a rules-based trading system. All of those things were in our interest. The point is not whether we should work with Russia. The point is whether we should sacrifice other important interests to do so.

I personally found Donald Trump's praise for Vladimir Putin troubling or even chilling, frankly. In a room full of military veterans, to be effusing about his great leadership and how strong he is and how popular he is, while disrespecting the American president and American generals, I don't know. That was, I think, not just troubling to me, but to a lot of listeners and I think, frankly, to a lot of Republican listeners as well.

One even tries to figure out why Donald Trump is so admiring of a leader who has cracked down on journalists and is suspected of using even violence, cracked down on civil society, ruling with an iron fist within Russia. To look with admiration on that sort of domestic leadership, I think is just really inconsistent with American values.

Secretary Hillary Clinton for four years was part of a policy of resetting Russian relations with Russia in our interests.

I was going to the heart of this matter, which is, the issue of whether Europeans should contribute more to NATO, I think, is a matter of consensus. I think Secretary Hillary Clinton believes that, and a series of U.S. presidents and secretaries of defense and state have urged our European partners.

While pursuing those relations with Russia, which are important - Russia is an important country - it is also important to stand by your friends and allies in Europe, defend your treaty commitment to NATO allies, stand by the sovereignty and territorial integrity of Ukraine. It's not whether we pursue relations with Russia when we need to, but what we're willing to give them in order to have that very, very good relationship that Donald Trump seems to be talking about.