George W. Bush warned Barack Obama that "the critics will rage (and) your 'friends' will disappoint you," while Obama urged current US President Donald Trump to "sustain the international order that's expanded steadily since the end of the Cold War." Anyone looking to advise the occupant of the Oval Office in January -- whether that is incumbent Trump beginning a second term, or a new President Joe Biden -- would do well to urge them to focus on the US relationship with China, which has cratered during Trump's time in office. Indeed, the President who takes the oath of office in 2021 may be the first in two decades whose biggest foreign policy challenge is not the wreckage left by Washington's twin invasions of Afghanistan and Iraq, but dealing with a new, multipolar world order where the US is no longer the sole superpower. China currently challenges the US for position as the world's largest economy, and, with a massively expanded...