Princeton historian David Bell calls it the Great Man Theory, as well he might. Journalist Steve LeVine writes in Quartz about the Big Personality Rule, which he foresees will dominate this year.

The Big Personality Rule, he explains, is “the impact of individuals whose idiosyncrasies can move and dominate events.”

Mr LeVine predicts that a “triangle of instability” will be formed this year by the US, Russia and North Korea, “all three of them wild cards, all led by men whose power emanates from a willingness to violate norms and be unpredictable, all seemingly gleeful to surprise and shock.”

The triangle of instability is a good way to describe it with new US President Trump as its hub.

For Kim Jong Un and his plans for an intercontinental ballistic missile have been around for a while. Ditto Vladimir Putin and his strongman aggression. But Donald Trump will be new on the geo-political stage.

The US will never have had a commander-in-chief who recklessly describes Nato as obsolete, smacks his lips at the possible break up of the European Union, and puts German chancellor Angela Merkel in the same category as Russia’s President Putin.

As Mr LeVine writes, “Trump’s posture, his bravado and bluster — and his plans to turn the US into a go-it-alone nation, not the world’s leader — make him the greatest geopolitical threat of 2017.”