I still hope that the American system of checks and balances will ultimately prevent this man, Donald Trump, with his erratic political style, from jeopardizing our European security architecture.

It was clear to me that the White House's solemn atmosphere would not civilize Trump. But the merciless nepotism with which he conducts politics, in which he places himself and his family above the law, I wouldn't have considered that possible. And on top of that there is this reduction of complex political decisions to 140 characters. When it comes to a U.S. president, I consider the reduction of politics to a tweet to be truly dangerous. Trump is a risk to his country and the entire world.

Trump is the freely elected president of the U.S. and as such deserves respect.

Primary responsibility for Brexit lies with British conservatives, who took an entire continent hostage.

I'm not a populist. But I try to present complicated issues in such a way that people know where I stand.

Gerhard Schröder offered a clear German NEIN to an American president's war of aggression that was in violation of international law. That took courage. Ms. Merkel did not join him at the time. If Trump now begins to take the wrecking ball to our set of values, we must say clearly: That is not our approach.

It is impossible to swear an oath to the German Basic Law without realizing that our constitution is among the most liberal constitutions in the world. As the head of government in such a country, I would stand up to all those who call into question this free, open and tolerant model of society.