What's the ONE thing you don't do? THREATEN DIPLOMATS.

https://www.huffpost.com/entry/trump-threatens-envoys_n_6a38b9fae4b0810d441d5732

While Vance was meeting with Iranian diplomats, Trump warned the delegation against keeping the Strait of Hormuz closed.

“You close it, and you won’t have a country,” Trump said on Fox News. “You won’t even make it back to your f**king country.”

Negotiators walked out in protest, and Stengel said they had every reason to.

“If there is one taboo in the history of diplomacy going back to the Peloponnesian War, is you do not threaten envoys, no matter how opposed you are,” he said. “And there he is, threatening envoys."

I'd say 'unbelievable,' but it's not..