Fired by tweet. Bullied by tweet. Insulted by tweet. Snubbed by tweet. Now President Trump brings his special skills to bear on Canada’s Prime Minister Trudeau. During public G7 diplomacy, neither one cared to keep his distaste for the other private, yet Trump’s snub at the end of the summit gives you a sense of his deep antipathy toward other people, toward the idea of friendship among nations.

The process of US isolation – where we snub allies, and allies respond ‘I suppose we don’t need that relationship after all’ – began with the Iraq war. Canada and UK excused themselves from that process. Now Trump takes care to insult his host Trudeau and Theresa May in public, during the most visible summit of the year. Trump knows how to complete the process of isolation and rapidly as possible.

We have an interesting contrast in this meeting, too. While Trump indicated during the week that he does not care to do polite business with Trudeau, he looked over at Putin in Moscow and said, ‘Look over there. We can do business with him! We need to invite him to be part of our G8 club!’ By his actions and manner, he practically asked the other six leaders at the summit to boot him out of the group.

An international friendship may take a generation or more to build, one or two insults to destroy.

An international friendship may take a generation or more to build, one or two insults to destroy. It does not matter whether Trump calculates his aims, acts by design or not. For that matter, all of the amazingly bad foreign policy decisions from the last eighteen years may or may not have had a motive that looked reasonable to decision makers. Whatever their aims, every one had predictably bad outcomes. We could make these estimates about outcomes before leaders executed those decisions. Not one of them was a bad decision only in hindsight.

So it is with planned isolation. If a friend leaves you or snubs you in public, energy required to restore the relationship may not be worth it. If you snub your friends, your former allies will make the same calculation. Is this guy worth it? What benefit exists if we indicate we would like to keep this relationship going? Clearly for Trump, the answer is that no benefit exists, for anyone. Except for Moscow, the US wants as little to do with its former friends as possible. Trump knows that public snubs end a relationship as quickly as possible. He knows how to be efficient.