"You've clearly never had the task of being a negotiator."
You need to match negotiating technique to the opponent. If you only use a single technique, intimidation for example, your opponents will adapt. Insult and intimidate seems to be Trump's go to, I hope he has more tricks up his sleeve than this.
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In my experience, posturing with Russians only leads to more posturing. There are times when this technique can be useful but not when nuclear weapons are on the table imo.