The prospect of a second Donald Trump administration has put the fear of God into America’s allies around the world. The biggest question being raised is: would the United States heave up the drawbridge and let others do the dirty work to keep the planet safe from global war?

Comments made by Trump seem to suggest he still has no love for Nato, that Taiwan should fend for itself if attacked by mainland China, and that Ukraine should give up the territory it has lost to the Russian invaders in return for a ceasefire and forgo any ambition to join the...