DW: What do you make over the row over this large Russian convoy that now has apparently come to a halt at the Ukrainian border? Moscow says is an aid shipment while Kyiv fears it could be a pretext for a Russian invasion.

Sestanovich: It looks as though this convoy issue is going to be resolved in the way that it should be - through international inspections and a role for the Ukrainian customs and border control officials.

The larger question of Russian aims, influence and interference in eastern Ukraine has not been resolved. And here there are very mixed indicators. One positive sign is that the Russian military intelligence officer who had been directing military operations in eastern Ukraine, Igor Girkin, appears to have stepped down.

This may mean that there is an opportunity for real dialogue between the Kyiv government and eastern Ukrainians. The Poroshenko government has said that it wants to negotiate with its own people, not with imported Russian agitators. If the Russians who have been leading the separatist effort disappear, that kind of dialogue may be possible.

During his visit to annexed Crimea on Thursday, President Putin said Moscow would do anything in its power to end the conflict in Ukraine. Do you believe him?

I think there are many reasons for Putin to wind down this confrontation. It has been a loser for him really since the annexation of Crimea, which was very popular in Russia and could have been ultimately accepted or at least put aside by Western governments.

But by pressing on with interference in eastern Ukraine and by apparent attempts to dismember the country, Putin has made enemies throughout Ukraine and mobilized opposition in Europe and the United States. He has seen those costs rise, but he hasn't yet made the decision to stand down. If his speech in Crimea is an indication that he may be ready to pull back that's very positive.

From your reading of Putin, what is his ultimate goal now for Ukraine?

It has seemed that his goal is to bring Ukraine under Russian influence. That could happen in a variety of forms - whether by bribing the Yanukovych government as he tried to do at the end of last year, or by seizing territory as he did in Crimea. But that goal has moved further from his reach. And right now, he has to decide whether he is ready to settle for a lesser goal, because he has lost the opportunity to dominate Ukraine in the way that he once aimed for. Now he has to decide whether he is prepared to live with a Ukraine that has significant institutional ties to the West.

Amid increasingly stricter Western sanctions against Russia being implemented, Germany's economy - which has big interests in Russia - shrank in the second quarter of this year. What's your take on Berlin's comparatively tough line vis-a-vis Russia in the Ukraine crisis so far and do you think that is sustainable?

I think it is clear that the German government did not want that confrontation with Russia and sought every means of avoiding it. But in order to avoid it completely, Putin had to show that he was ready to deescalate. And instead he continued to interfere in Ukraine at every key moment when it seemed as though the West was divided over new measures against Russia, and Putin poured new men and materiel into Ukraine.

The shooting down of the Malaysian airliner was of course the decisive moment, and the insistence by Putin that it was the fault of the Ukrainian government - when it was clearly his own interference that had produced this tragedy - I think left the government in Berlin and government's across Europe with no choice.

Stephen Sestanovich served as US ambassador-at-large to the former Soviet Union between 1997 and 2001. He is currently professor of international diplomacy at Columbia University and George F. Kennan Senior Fellow for Russian and Eurasian Studies at the Council on Foreign Relations.