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.

We're hopeful that Russia will choose to play a constructive role in supporting ceasefires through their own Astana talks, but also, ultimately, through Geneva. And if we can achieve ceasefires in zones of stabilization in Syria, then I believe we will have the conditions to begin a useful political process.

I think what we're hopeful is through this Syrian process, working with coalition members, working with the U.N., and in particular working through the Geneva process, that we can navigate a political outcome in which the Syrian people, in fact, will determine Bashar al-Assad's fate and his legitimacy.

I've made my own comments as to our vales as well in a speech I gave to the State Department.

I think the Russians need to think more carefully about the commitment they made under the chemical weapons agreements to be the guarantor that these weapons would be seized, they would be removed, they would be destroyed. And since they are Bashar al-Assad's ally, they would have the closest insight as to the compliance.

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.

Russia and the USA are two largest nuclear powers in the world; it's a really important relationship. How do we start making this work? How do we live with one another? How do we work with one another? We simply have to find a way to go forward.