In the run-up to the ongoing G20 meeting in Hamburg, I was interviewed by the G20 Research Group about its significance. I argued that the only really important issue was whether the United States would at last be induced to signal a commitment to the idea of a global community or would it double down on atavism.

As I write Saturday morning (US time), things seem to be running below my already low expectations. On the philosophical and policy questions regarding United States’ willingness to continue supporting a rules based international system, there is no progress to observe.

On the question of the character of the US President–the most powerful person in the world–there is new and disturbing evidence. President Trump has deemed the survival of the West to be the issue of our time. In context, his statement cannot be read as anything other a call for a dangerous clash of civilizations. It will surely raise doubts in Asia, the Middle East and Africa about the reliability of American support for its allies.

At a time when the elephant in the room is his own mental stability, the President has confirmed doubts by bizarrely tweeting about how leaders are preoccupied by Hillary’s campaign manager.

It is the tragedy of this moment that our President, and how he causes himself to be perceived, is the greatest threat to our security.