An argument in the White House tore apart the US alliance with Ukraine, shook European leaders and highlighted JD Vance's key role in forcefully expressing Donald Trump's foreign policy. The vice-president has come out punching on the global stage - so what is it that drives his worldview? Vance's first major foreign speech, at the Munich Security Conference in mid-February, caught many by surprise. Rather than focusing on the war raging in Ukraine, the US vice-president only briefly...