I think the President Donald Trump was quite clear in his statement that he made to the American people that Syria's continued violations of U.N. resolutions and previous agreements that Syria had entered into regarding the Chemical Weapons Accord would no longer be tolerated. I think we have stood by and watched multiple weapon - chemical weapons attacks by the Syrian regime under the leadership of Bashar al-Assad.

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 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.

It's important that we keep our priorities straight. And we believe that the first priority is the defeat of ISIS. That by defeating ISIS and removing their caliphate from their control, we've now eliminated at least or minimized a particular threat not just to the United States, but to the whole stability in the region.

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.

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.

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.