You don't have to compete against each other, you can also think carefully: what does he want, what are his interests?

"I think we sometimes dismiss him too easily as an idiotic clown, there is really a rationale behind it," says chairman Tim Masselink of the Dutch Association for Negotiators. "Polite requests don't always work internationally, so if you are seen as someone who not only bluffs but also actually issues decrees, then that has an effect."

According to Masselink, Trump's tendency to throw a stick into the diplomatic henhouse is in his nature. "He comes from a different sector, of course. He is a real estate entrepreneur, a street fighter who thinks in winners and losers - and sees himself as a winner."

Read the full interview with Tim on the NOS website (Dutch).