Donald Trump is hardly the first US president to look south and conquer. Over the last century, no fewer than a dozen of Trump's predecessors embraced the belief that democracy and profit in Latin America were only one successful coup d'état away. But the particular strain of imperial ambition that Trump appears to have set loose with this weekend's raid in Venezuela appears simultaneously to be deeply atavistic and uniquely Trumpian. And it's one that doesn't look set to die down anytime soon.