I think the Russians have played now for some time the role of providing cover for Bashar al-Assad's behavior. The alternative explanation that the Russians put forth is simply not plausible.

The increase in the greenhouse gas concentrations in the atmosphere are having an effect. Our ability to predict that effect is very limited.

Once the ISIS threat has been reduced or eliminated, I think we can turn our attention directly to stabilizing the situation in Syria. We're hopeful that we can prevent a continuation of the civil war and that we can bring the parties to the table to begin the process of political discussions.

Our priority in Syria, really hasn't changed. I think the President Donald Trump has been quite clear. First and foremost, we must defeat ISIS.

Obviously, the United States' own founding principles are self-determination. And I think what the United States and our allies want to do is to enable the Syrian people to make that determination. You know, we've seen what violent regime change looks like in Libya and - and the kind of chaos that can be unleashed.

People who speak up for freedom in regimes that are oppressive are often a threat.

I think continued actions by Bashar al-Assad clearly call into any question of him expecting to have any legitimacy to continue as the leader of Syria. With each of those actions, like attack with conventional weapons, barrel bombs and block humanitarian aid he really undermines his own legitimacy.