From day one, Donald Trump vowed to take a tougher line with America's enemies - a stance reflected in some caustic Twitter exchanges with North Korea's leader.
But, in a move that stunned the world, the bellicose rhetoric soon gave way to an historic rapprochement. Over the course of his presidency Trump met Kim Jong-Un three times.
"I think our whole relationship with North Korea and the Korean peninsula is going to be a very much different situation than it has in the past," Trump said at the time. "We both want to do something. We both are going to do something and we have developed a very special bond."
It was an accelerated diplomatic drive Joe Biden is unlikely to continue if he prevails in the November election. Trump's critics say his relationship with Kim delivered more in the way of warm words than North Korean nuclear disarmament.
In contrast, under Trump, US relations with China have hit their lowest level in decades, primarily amid a trade dispute. But Trump's decision to blame China for America's coronavirus woes has heightened tensions and trade talks are now frozen. Biden says he would continue to pressure Beijing, but through a multilateral approach, involving US allies.
But it's perhaps over Russia the two men differ most strongly. Trump has seemed reluctant to criticise President Putin at times, even when US intelligence concluded the Kremlin had interfered in the 2016 election.
Biden has signalled he would take a much firmer line with Moscow:
"The fact is that I have gone head to head with Putin. And made it clear to him we're not going to take any of his stuff. He's Putin's puppy."
But Biden appears unlikely to reverse one of the signature foreign policy developments of the Trump presidency; the transfer of Washington's Israel embassy from Tel Aviv to Jerusalem.
He would, however, seek to reset America's ties with its allies, many of whom were heavily criticised by Trump. Ultimately, for the average US voter foreign relations are rarely an election priority, even more so now with an unprecedented health and economic crisis at home.