Early in his presidency, the United States' Donald Trump is grappling with how to respond to North Korean leader Kim Jong-un's threats of nuclear war.
An Asia-Pacific expert at the Australian National University, Michael Wesley, says it is the biggest foreign policy challenge facing the new president.
"The big question that Trump's got in front of him, for all of his bluster, 'Are you going to be the president that allows the North Koreans to develop the technology to deliver a nuclear weapon direct to the US mainland during your presidency?' That's the big, stark question in front of Trump, and pressuring the Chinese is a way of kicking the can down the road* for the moment."
President Trump has been pressuring China to exercise its economic leverage over North Korea.
But Professor Wesley has told the National Press Club in Canberra there is a limit to what economic pressure from China can achieve.
"We need to remember that North Korea developed most of its nuclear technology and capability while most of its people were starving. This is not something that is a rational calculation for the North Koreans, this is something that is existential for them."
Donald Trump's election campaign promised an "America First" trade policy that included new taxes on foreign imports.
A macroeconomics analyst at ANU, Professor Warwick McKibbin, warns a sudden hike in tariffs would likely lead to retaliation, as well as a global recession.
He says he does not think that will happen, because Mr Trump's economic advisers will caution against it.
But he does predict a more gradual, rising protectionism that could cause a trade war in three or four years.
"Once the fiscal policies are in place, and once the imbalances in the external accounts get worse and worse and worse, somebody has to be blamed. You won't blame the administration who's implementing the fiscal policies that are causing the problem, you'll blame the foreigners. So I think, although a trade war is unlikely in the near term, I think we're setting up a set of macro policies which really push in the direction of a potential response."
Prime Minister Malcolm Turnbull is now scheduled to meet with President Trump for the first time next month.
The ANU analysts say they expect Mr Turnbull to try to strengthen his relationship with the President after a frosty phone call between them earlier in his term.
Michael Wesley says Australia's approach to the US alliance should depend on how long Donald Trump remains in power.
"If he's a flash in the pan, if he's only around for four years, my counsel would be, you know, 'Keep your head down, and just rely on those underlying structures of the alliance to take us through.' If he's a longer-term trend, then we've got some much more profound questions to ask ourselves about how close we want to be to the United States in the long-term future."
Meanwhile, at a speech to the Lowy Institute research centre in Sydney, former prime minister Paul Keating said Australia should keep America close -- but not rely on its traditional ally.
"We keep the Americans as the floating good guys. We keep them in the balancing role. But we determine a foreign policy of our own that looks after Australian interests in the new order -- the new order which will have China as the centre of gravity."
