I'd argue compared to the UN itself the Trump administration is positively polite. Take the last few ICC incidents. South Africa and Mongolia have in the past 2 years publicly used the ICC for proceedings AND taken very, very, very public action ... to protect individuals convicted at the ICC against the court. And then there's Saudi Arabia, and allegedly India using diplomatic personnel as assassins.

https://www.bbc.com/news/articles/cwy527yex0no

https://www.bbc.com/news/world-africa-33157407

https://www.bbc.com/news/world-africa-65759630

There's another semi-country that has done a lot worse, even more publicly, but I don't want to turn this in the 20th Israel discussion.

When push comes to shove you have 3 groups at the UN:

1) the US, and to a much lesser extent France and UK, who are the only members of the UN security council that actually do anything to enforce UN principles. And frankly, they are generally attacked for doing so, and attacked when they decide not to.

2) there's countries that will provide lip service to UN principles but won't take action (and violate UN principles on a small scale themselves e.g. all European prison systems, oh and including Israel's and Canada's). Or who will, at most, provide small amounts of support to US efforts. I'd say this describes 80% of the EU, Canada, Switzerland, a few others. And of course, very publicly, it describes Israel. Israel definitely used to be in group 1, making significantly more than token efforts to support the UN, despite having no power in the security council. That hasn't stopped, but it gets sabotaged to the point of nonexistence.

3) countries who actively oppose UN principles, at the UN, in word and deed. This describes 20% of the EU (e.g. Hungary, Serbia, ...) and essentially everyone else (including security council members Russia and China, all muslim countries. Turkey used to be the exception, more in group 2, but not anymore, under Erdogan)

So you could as well say it's more of a case of the US joining the EU's style of politics. But many people would consider that offensive.

More general I would say it's the evolution we're seeing towards war. 5 years ago there were 3 active conflicts, and 100 "frozen" ones. 2 years ago there were 10 active conflicts. Now there are at least 30 active wars and increasing. Sadly, it isn't as simple as this being Trump's administration or any individual government's doing, in fact I am of the opinion that Trump's administration is trying to stop it, and on the other side Russia and China definitely deserve to be called out as a major cause. A lot of countries now sabotage international cooperation for political and ideological reasons rather than cooperate, with China's actions against shipping in the pacific (Taiwan, Philippines, Vietnam, even Australia at times) as currently as the worst example, but far from the only one (Russia, boycotts against Israel, ...), and it certainly seems like it's still getting worse. For 3 years now we're doing about 1 new armed conflict breaking out every 2 months.

It reminds me a lot of the pre-WW1 situation. Plenty of groups of countries that are belligerent as groups. EU/Turkey/Israel vs Russia/North Korea/Iran/"the non-aligned movement" who are doing trench warfare. US/Taiwan/Phillippines/Indonesia/Australia vs China. India vs Pakistan/Iran/Afghanistan. Muslim countries vs Africa. All of these groups have either constant naval warfare or entrenched warfare.

It's not (and I never expressed surprise about it, because I suspected the administration was lying all along), but generally I expect administrations to lawyer-dishonest - eg relying on loopholes, technicalities, fallacies, or debateable half-truths to accomplish some legal objectives.

Deliberate misrepresentations of basic are grounds for more drastic outcomes like summary dismissal with prejudice, impeachment, general loss of legitimacy.