Robert Zoellick was the US Chief Negotiator for the 2+4 negotiations that led to German unification. He also served in various other key positions including US Trade Representative, Deputy Secretary of State and President of the World Bank.

DW: There are special events in people's lives when they can remember forever exactly where they were and what they did that day. For many Germans the day the Berlin Wall was opened is such a day. Do you still remember where you were that day and how you reacted?

Robert Zoellick: Yes, I was at a luncheon that US Secretary of State James Baker was hosting for the president of the Philippines. We were up on the 8th floor of the State Department and it was a very large gathering and someone passed Secretary Baker a note about the opening of the wall. We were all obviously amazed as was the rest of the world and I remember that after lunch we got together and had a quick discussion about what this meant and what we needed to do next.

But what also upon reflection is still so striking is the rapidity of change. I also remember a meeting in early 1989 that Secretary Baker had with his former finance minister colleague [Gerhard] Stoltenberg who was then the defense minister. I remember going up to some German officers before the meeting and asking them what does the German public think about reunification. They were reserved, but they were starting to explain what they thought and up came at that time the assistant secretary for Europe and she asked what are you talking about and we said German unification. And she said the subject that all Americans are interested in and no German cares about. And I thought she totally missed what was in the air.

Probably most people in Germany and beyond didn't expect that Germany would be reunited in their lifetime. Honestly, did you personally believe before 1989 that you would live to see Germany united again?

I certainly wouldn't have predicted unification in that timeframe. But relatively early on we saw that the ice was breaking in the Cold War and we had to be prepared for a series of eventualities.

But to put this into a little of perspective and most people, even historians, overlook this. Relatively early in his tenure President Bush made a rather bold move at the May NATO summit where he moved the agenda away from the nuclear arms control that had dominated the late Reagan years to a very aggressive proposal on conventional forces, to both lower and equalize them in Central and Eastern Europe. This was in part a way of getting ahead of the debate on short-range nuclear forces, because short-range nuclear forces would be less important if we created a conventional balance. But it was also a way of changing the dynamic to a sense of getting Soviet forces to leave Central and Eastern Europe. So that NATO summit in May becomes very important in establishing Bush's leadership of the alliance, moving the short-range nuclear issue to the side and starting to build what became a very important and indeed historic partnership with our German colleagues, both Chancellor [Helmut] Kohl and Foreign Minister [Hans-Dietrich] Genscher.

Was it really always clear for the Bush senior administration and for you personally that Germany should be reunited again?

This is really one where we, at least the close team starting with President [George H.] Bush, definitely were on the right side of history. I always felt that this was a promise that the United States had through NATO and 40 years of the Cold War to the German people. But it was also something that Americans shared in the prospect of uniting a democratic Germany. What actually made the diplomacy easier from the US perspective than in Britain, France or Italy or elsewhere was that the American people were naturally in sympathy of the idea of Germany uniting.

President Bush actually gives an interview - I think in May - where he talks about unification relatively early on and he welcomes the idea. So we both had a sense of that being a responsibility to an alliance partner, but it also reflected a strategic judgment - and that was my view and that has been borne out some 25 years later - that a united Germany would become the most significant country in Europe and that it was important from a strategic perspective for the United States to build a partnership with Germany within European structures, both the European Union and NATO, for the future.

But I'll give you another perspective on a personal note. This one comes from December 1989. So the Wall just opened - and this reflects the debate about what was going to happen to the East - the US state department personal in East Berlin were in touch with the very courageous dissenters, many with the Lutheran Church. They were talking about "Der Dritte Weg" (The third way) and trying to create a different sort of structure for East Germany. When Baker and I went to the Nikolaikirche in Potsdam on a dark December night, I recall, it was very moving that the pastors and many of the lay people who were really courageous and stood up against the totalitarian regime were acknowledging that most East Germans didn't want the third way. They wanted what their cousins in West Germany had. And that was a momentum that led us to conclude that this would not be a merger, but it would be a takeover. And that had implications how this could be achieved under the German constitution, Article 23, but it also had implications for the diplomacy.

Speaking of diplomacy, during the 2+4 talks, what was the hardest nut to crack?

In the early stages - President Bush and Secretary Baker did tremendous work on this - we had to make sure we had a common alliance position. There was reluctance on the part of France and Britain. At one point, President [Francois] Mitterand seemed to suggest to President [Mikhail] Gorbachev that there may be a way to stop this. And it is quite interesting, the record shows that Gorbachev was suspicious that the French might be setting up the Soviet Union and he preferred to follow a course to work with Chancellor Kohl and President Bush. But later the real challenge was how to try to achieve a united Germany within NATO and within European structures that would create reassurance for others in Europe, but also create an architecture for future security stability in the transatlantic area and with the then Soviet Union.

Events were moving so fast that the Soviets were caught off balance and yet this is where the public dynamic is quite important. The people on the ground were pushing and forcing the issue. The Soviets obviously wanted to slow it down. They didn't want to have unification and they were trying to preserve the status quo. But then we had to try to particularly work with our West German partners to frame an explanation for the Soviets that preserved their sense that this would not be to their disadvantage.

It was my office that come up with the suggestion that of not necessarily doing it with all the players in CSCE [The Commission on Security and Cooperation in Europe - the ed. ] or the four powers alone, but to create a 2+4. And it was conscious that we put the 2 in front of the 4, because we were emphasizing the two Germanys were in the lead with this. This was something we had to sell to the Europeans and the Soviets. We were able to do that early in 1990 and then were able to create the process itself. There were people who said we shouldn't create any process and just let events take its course, but President Bush and Secretary Baker decided that was too risky because the Soviets still had 400,000 troops in East Germany and they had their four power rights. So we had to reach a sort of safe landing pad for all the participants.

What's your assessment when you look at a united Germany today, 25 years after the fall of the Wall?

I think it has been a great success. I always suspected at the time that the internal unification would take longer, because the effects on people in the East I thought were going to not be easy to overcome.

On a larger stage, Germany is now debating what obligation its influence creates. We have certainly seen this in the financial crisis in the economic role of Germany. But President [Joachim] Gauck gave a speech at the Munich Security Conference this year that invoked a series of questions about what Germany's larger responsibilities in the world, whether dealing with Russia-Ukraine or the Middle East, Africa, China and I think that's a healthy debate for Germans to have.

Only Germans can make these decisions, but my own view is that while it's inevitable that there will be differences between the United States and Germany on various issues, as I survey the horizon and diversity in the world, there is going to be more commonality between Americans and Germans and other Europeans and that is something that you need to continue to work on.

One small diplomatic element which I think is a bit ironic, but understandable: My German colleagues were under great pressure, because this is a historic moment for their country. But sometimes I was more protective of a future German sovereignty than they were, because they were perhaps tempted to accept little compromises. But my view was from the long-term perspective we needed to complete unification in a fashion that established Germany as a normal, sovereign country. Because I didn't want future generations of Germans to say 'why are we being treated differently'?

But ultimately it comes down to the people. The German people were the moving force on this and you asked about pride of the events. I am proud that sometimes the American people get in trouble around the world because they think others think like the Americans do, but in this case the fraternity with freedom ended up being a wonderful contribution because unlike many in Europe the American public naturally said, 'of course the Germans want to be united and free and democratic. So we should support that.'