"It's quite reckless behavior," says Anders Lidén, a former UN ambassador with 37 years of experience in diplomacy.
He thinks he sees a pattern in the American president: breaking down institutions and regulations so that he and the United States can fully use their power.
"When he puts forward these ideas about a peace council, for example, it's a way to bypass the UN. When he's aggressive on the Greenland issue, he bypasses NATO and ignores it."
Greater room for maneuver
Even diplomacy, with its many established rules and customs, can be seen as a kind of institution, and Donald Trump is now violating all of that.
"He doesn't have to worry about humiliating or insulting another person - he can even post what someone else has written, perhaps in confidence," says Lidén.
Trump can do that, because a great power always has more room to maneuver. Representatives of small states must always think about the future and build trust and confidence. But even for a great power, such behavior means that trust is lost, notes Anders Lidén.
"I don't think he thinks about the fact that even a great power needs to have relationships with other countries over time, and that's what he risks damaging."
The US is challenged
The same applies when Trump disregards international law and international regulations, he emphasizes.
"The US is not becoming stronger internationally, but is being challenged by other powers that can exploit this, and then the Americans can also be exposed to violations of the rules that they don't really like."
"I think rules are good for everyone, but it's clear that they're best for the small states. The big ones may not always realize that rules are good for them too."
