United States President Joe Biden's whirlwind tour of Europe - his first foreign outing since he took office - was ostensibly designed to repair relations with some of America's closest allies.

But the key underlying message of his trip - and one otherwise barely mentioned in all the communiques issued at the end of the various summits - was to rally Europe to the confrontation that the US President is convinced now lies ahead: the battle between Western-style political systems and China.