Russia has the ability to control Ukraine's economic future because of the natural gas pipeline link. And as a result, that means that Russia has just all along been in a stronger bargaining position.

I don't think that we're necessarily going to see the U.S. and Russia becoming out and out military competitors against each other.

Vladimir Putin doesn't really gain anything economically from annexation of Crimea. It's more a gain of power. It's a gain of what he can say to his home population about what he's accomplished as president. And so it's really much more an individual gain for Putin politically than for Russia as a state, because over the long term, Russia is not going to particularly benefit from this.

I think Russia must have been very embarrassed by Syria's use of chemical weapons because it really undercut Putin's role back in 2013 in saying he had helped get rid of Syria's weapons.

I'm not sure about whether Ukraine will ever be joining. As long as there's a frozen conflict on Ukrainian territory, they can't possibly join. And that's probably one of the reasons why Vladimir Putin is interested in having a frozen conflict there, so that there is no border security.

Russia has the ability to control Ukraine's economic future because of the natural gas pipeline link. And as a result, that means that Russia has just all along been in a stronger bargaining position.

Putin is somebody who really respects strength.