DW: Mr Schäuble, you had a major role in negotiating — indeed, in writing — the Treaty on German Unity.When you look at Germany now, three decades later, is this what you imagined then? 

Wolfgang Schäuble: No, but where in the world has anyone ever been able to imagine what is going to happen in thirty years' time? In these past thirty years, too, Germany, like the whole world, has totally transformed. There is no longer a leading world power keeping order.

For some time the United States appeared to be almost the only remaining superpower. But the world has become more diverse. We could never have imagined, back then, how the East-West conflict would come to an end. But then it did end, miraculously, without war, almost without deaths. And yet that didn't make the world a safer place. Instead, wars were possible once again. Only a few years later, in the middle of Europe. 

Read more: German reunification: What still divides East and West?

Germany's reunification would not have been possible without the United States' role as an ordering power. Now the US is stepping back from world affairs. Are you concerned that America could become a force for disorder? 

No, I wouldn't say that. I mean, we Europeans, all of us, owe the fortunate developments of the postwar era — fortunate at least for western and central Europeans, less so for eastern Europeans, who had a tougher time — to the fact that the Americans learned a lesson from the First World War and the period between the wars, namely that they must stabilize Europe to prevent a repetition. 

And now the world has totally changed, which is why the chancellor was correct in 2017 when she said, "We will need to take on a greater share of responsibility for our own security." But I hope that in the future we can continue along that path because we share common values, the basic principles of human dignity, democracy, freedom, the rule of law, and also ecological sustainability and social justice. They distinguish us fundamentally, for example, from the very successful Chinese model, which today does hold great attraction, but at the price of total control of the whole of economic, social, and political life. And that's not our vision of how to live.  

That's why we must try to demonstrate the superiority of a peaceful, balanced order based on ecological sustainability, geopolitical stability, and the principles of western values. We Europeans cannot do that alone. But we need to take a greater share. And the more we take on responsibility and relevance — economic, political, also military — the more we will influence the debate, also in America. Because if we're relevant, we play a larger role than if we're not.  

At the time of reunification, many were fearful of a newly strengthened Germany. Now, there are increasing calls for Germany to play a stronger role. Is Germany still too reticent on the world stage? 

About this fear of a stronger Germany — the situation was a bit more complicated. There were of course, understandably, these concerns in Western Europe. British Prime Minister Margaret Thatcher was known to have such concerns, the reaction from Francois Mitterrand was similar. In the first few weeks after the fall of the Berlin Wall, the most reliable support in Europe for Chancellor (Helmut) Kohl actually came from the then Spanish Prime Minister (Felipe) Gonzales. Otherwise, most of them were a bit cautious. They were wondering what it would mean if 40 years after the Second World War, Germany is again the largest, most populous, and economically the strongest country in Europe. 

Read more: No unity 30 years after the end of the Cold War

But that passed relatively quickly, especially because they understood that this unified Germany was more a reliable partner in European integration and that this served their interests.

A Polish foreign minister said in a speech not that long ago: "We used to fear the strength of Germany - today we rather fear the opposite." You can still feel the enormous resistance to this in the German population and thus also in the political parties in Germany, including in parliament. And yet we have to get used to the fact that others expect us to bear a fair share of the common burden. 

Thirty years after reunification there are still big inequalities between East and West, especially economically. And right-wing populist parties are stronger in the East. 

I would be a little more cautious about Germany. The economic differences have become smaller. But the consequences of 40 years of our social market economy were clear then: Full integration into the European Union and into open world trade on the one hand — and on the other, the socialist, bureaucratic state economy, which was just not competitive. Not least because of this, the Eastern bloc as a whole collapsed. It was not able to create living conditions for its citizens as successfully as the liberal order was. The liberal order, including the social market economy, was just superior. That has left deep differences. You can feel them all over Europe.

Read more: Who can save the liberal world order?

The people in the GDR did not have the opportunity to experience living together with people who came to our country from other parts of the world. So it is not surprising that people who were not used to immigration, perhaps people arriving with different skin color or a different religion, can be more easily mobilized with populist slogans. And this does not only apply to former East Germany. Take a look at the debates in the Czech Republic or in Hungary or in Poland. You can't blame people for that. 

I also want to emphasize: Although we (Westerners) now have a third generation of immigrants living here since the early 1960s, whose grandparents or maybe even great-grandparents came to Germany from Turkey, we still have considerable problems in many parts of western Germany. And that's why we West Germans shouldn't be arrogant towards East Germans.

Reunification would not have been possible without Russia either. But the current Russian President Vladimir Putin feels cheated by history. Has the West failed in its dealings with Russia? 

When Putin came to power, he pursued a policy in which, to a certain extent, he wanted to repair the humiliation of the Soviet Union he believed people felt — and he tried that in his own way. He's not right about Crimea, but we do need better, fairer cooperation with Russia. Perhaps not everyone in America understood this or handled it correctly in the important years. We must try to achieve better cooperation with Russia — fully respecting Russia's claims and history. And, by the way, we must also cooperate with China.

Without reunification, the emergence of Angela Merkel as a politician would not have been possible. At the moment, many people cannot imagine a Germany without Angela Merkel after 2021. Can you imagine that? 

You know, I grew up at a time when one couldn't imagine the Federal Republic of Germany without Konrad Adenauer. To that extent, yes: Angela Merkel lived in the GDR and would not have become a German chancellor without reunification. But she is a woman of very extraordinary qualities. And that distinguishes her from her predecessors. It seems that she herself will be able to determine when she leaves office. My wife told me a long time ago: "You men never give up voluntarily. Ms. Merkel is different from the men. She will say for herself when it's enough." It seems she can do that. 

Read more: Wolfgang Schäuble tells eastern Germans to stop playing the victim

And after that, life will go on. I believe we will still be a strong, free democracy based on the rule of law in ten years' time. We will find a new chancellor. The voters will decide. She will no longer be available. But Germany will go on. And so will Europe. 

CDU-politician Wolfgang Schäuble is president of the German parliament, the Bundestag, of which he has been a member for 47 years. Thirty years ago, Schäuble played a central role in negotiating the Treaty of Unification. He was a government minister several times. 

Schäuble was speaking to DW's Michaela Küfner.