We shouldn't be lowering standards for NATO membership; we have to insist on democracy, reform, market economy, anti-corruption, reformed military, contributions to common security, interoperability - all the things that the Czechs had to do, the Poles had to do - they're still on the table. Which means that Ukraine is a long way away from getting to that point.

People want strength. They want American values. They want American interests. They want to be successful. And I'd say that's on both sides of the aisle, as well as any divisions even on the Republican side.

I think in Russia's case, they want to have a Ukraine that is pro-Russian, Russia-friendly, a government they can work with. And yet, by invading the country and taking part of the territory, they've produced a more nationalist, more Western-oriented, more unified Ukraine than ever existed before.

The way I think of it is that Russia is not going to change fundamentally. They may change tactics; they may look at their interests and figure out what actions they take, but they're not going to change fundamentally. And they're going to try to gauge what will the responses be to things that they do, and what will our things be. And here, they do wonder what is the level of our resolve? How far are we willing to go? And that is something that is very hard to gauge.

We shouldn't be lowering standards for NATO membership; we have to insist on democracy, reform, market economy, anti-corruption, reformed military, contributions to common security, interoperability - all the things that the Czechs had to do, the Poles had to do - they're still on the table. Which means that Ukraine is a long way away from getting to that point.

The big issue is whether Ukraine is successful as a country. Democracy. Market economy. Prosperity. Security. And so on. And whether we can resolve this conflict, which I think is an important step in restoring sovereignty, restoring territorial integrity in Europe, getting beyond the impasse that we have with Russia now, that's where we would like to go.

I actually think that the Russians are exploring the idea: Is it worth ending this conflict in the Donbass in eastern Ukraine, creating peace, getting out, and what would that look like? I don't think they're committed to it yet; I don't think they've made a decision one way or the other - but I think they're exploring it.