[Recep Tayyip] Erdogan is an adherent of realpolitik. He knows that international relations are not built on the strength of unilateral demands, but on solutions that are in everybody's best interest.

At the end of the day, men like Donald Trump need to be given that which they themselves dispense: clear messages. I would confront him as clearly and explicitly as possible. It is not only the right, but also the duty, of the leader of a German government to do that.

Businesses will only invest in Greece if three conditions are fulfilled. First, there must be a clear commitment to the euro. No businesses will invest if they have to fear that Greece will leave the euro zone at some point. Second, the Greek government must be prepared to work together with European institutions in order to restructure the country.

Complementing the nation-state as it reaches its limits amid globalization: That is what Europe must offer.

Turkey is doing an enormous amount in the refugee question, but it can't continue to pay for everything by itself. That is why we have to talk to Turkey about money.

Germany is not a fair country. Millions of people believe that things aren't fair in this country. Company profits and bonus payments have increased at the same rate as precarious employment situations.

It was a Russian airplane that was bombed over the Sinai Peninsula. When the Russians conduct air strikes on IS, they are doing so because they too are threatened by terror.