A Joe Biden presidency would seek to reinvigorate America's alliances with countries such as Australia to bolster multilateral bodies and tackle a China that has overstepped the mark, former US ambassador to the United Nations Samantha Power says.

But despite Donald Trump ramping up anti-communist rhetoric and imposing some diplomatic and economic sanctions, the US people have no appetite for conflict with China because of "war fatigue" following the protracted commitments in Iraq and Afghanistan, Professor Power says.