Successive US presidents have struggled to get the measure of Vladimir Putin but now that Brussels and Berlin have joined the fray with such resolve, it's a different story, writes Nick Bryant.
It is often tempting to look upon Vladimir Putin as the millennium bug in a human and deadly form.
The Russian president rose to power on 31 December 1999, as the world held its breath that computers would go into meltdown when the clock struck midnight, unable to process the change from 1999 to 2000.
In the 20 years since, Putin has been trying to engineer a different kind of global system malfunction, the destruction of the liberal international order. The former KGB spymaster wanted to turn back the clock: to revive Russia's tsarist greatness and to restore the might and menace of the Soviet Union prior to its break-up in 1991.
This Russian revanchist has become the most disruptive international leader of the 21st Century, the mastermind behind so much misery from Chechnya to Crimea, from Syria to the cathedral city of Salisbury. He has sought - successfully at times - to redraw the map of Europe.
He has tried - successfully at times - to immobilise the United Nations. He has been determined - successfully at times - to weaken America, and hasten its division and decline.
