Donald Trump arrives in Da Nang on Friday, a seaside resort chosen by Vietnam to hold the Asia-Pacific Economic Cooperation (Apec) conference. The resort will be filled with other world leaders and offers up the possibility of some unpredictable meetings.
Russian president Vladimir Putin
Trump’s relationship with the Russian president is a colossal issue in Washington. Any meeting will be forensically analysed back home.
A face-to-face talk would take place directly after fresh details emerged of an ambitious plot by a former Trump campaign foreign policy aide to arrange a meeting with Putin ahead of the election – the most explicit evidence yet of a campaign official’s attempts to work with the Kremlin.
The revelation, and the indictment by the FBI of two other Trump associates, has added to the view held by Trump’s political enemies that the president or his campaign coordinated with Russia to manipulate the US election.
When Putin and Trump met at the G20 in July, the talks lasted two hours and 16 minutes – far longer than expected – and the pair later had an undisclosed second meeting where Trump was the only US official present, adding further intrigue.
Philippine president Rodrigo Duterte
This is one to watch: two of the world’s most bad-tempered leaders with a penchant for unscripted remarks, both in the same room.
Duterte, a former mayor nicknamed “the Punisher” who once braggedabout killing a man by throwing him out of a helicopter, pulls no punches when commenting on other leaders. He called Barack Obama a “son of whore” after the former president criticised his bloody war on drugs, in which police have killed thousands and been accused of extrajudicial killings.
Possibly bonding over their mutual dislike for Obama, Trump and Duterte have got along well. A senior US official said the two had a “warm rapport” and a leaked copy of a phone call between them revealed Trump praising the Philippine leader for an “unbelievable job” in the fight against drugs. However, both strongmen-style leaders tend to fall out with people, often publicly.
The pair might not meet in Vietnam but they are already scheduled for a bilateral on Monday in Manila, the final leg of Trump’s tour, at the Association of Southeast Asian Nations summit.
New Zealand prime minister Jacinda Ardern
A day after Trump’s inauguration, Jacinda Ardern, an MP for the Labour party in New Zealand, joined thousands in Auckland as part of a global women’s march. It had been organised as a rebuke to the election of a billionaire once caught on tape bragging about his ability to “grab” women “by the pussy”.
The 37-year-old took the party’s leadership in August and went on to become the youngest New Zealand PMin 150 years, and the country’s third female leader.
There are signs that Ardern would not allow a sexist remark from Trump to go undefended. In August, when asked by a radio host if women should tell their employers if they planned to have children, she responded angrily, saying: “It is totally unacceptable in 2017 to say that women should have to answer that question in the workplace, it is unacceptable, it is unacceptable.”
In an interview with the Guardian before her election, she said she would be “a diplomat” in any meeting with Trump. “Despite us coming from different parts of the political spectrum, that is not new for world leaders and I have to respect democracy and the people who’ve chosen their leader in the United States.”
Australian prime minister Malcolm Turnbull
Their first call in January, a copy of which was leaked in August, was an acrimonious exchange that Trump told Turnbull was his “most unpleasant call all day”.
The pair clashed over a deal, brokered by Obama, for the US to accept hundreds of refugees currently held on Manus Island and Nauru under Australia’s offshore detention programme.
“I think we should respect deals,” said Turnbull, who has been criticised for the desperate conditions in the camps. Even Trump asked why he hadn’t “let them into your society?”
A clearly unhappy Trump said the deal was “stupid” and would “kill” him politically, given his status as “the world’s greatest person that does not want to let people into the country”.
Turnbull and Trump later attempted to clear the air during their first face-to-face meeting in New York in May, where they were all smiles and compliments. But only about 50 of the 1,250 people agreed under the Obama deal have since been accepted by the US government. And pressure has mounted on the Australian leader to find a solution.
Malaysian prime minister Najib Razak
These two are golfing buddies, and Najib keeps a photo of Trump on his desk.
But the relationship is overshadowed by a corruption probe into Najib that is being conducted by the US justice department, the largest foreign kleptocracy investigation ever launched.
The veteran prime minister faces allegations that billions were stolen from a sovereign wealth fund, 1Malaysia Development Berhad, in complex overseas deals.
While both the prime minister and the fund deny any wrongdoing, the justice department has filed civil lawsuits to seize assets, from top-end real estate to famous artworks.
Trump has avoided the issue, but the Malaysian leadership is sensitive to anything that might be seen as a snub by Trump.
Najib might be hankering for another photo op and has played up his Washington visit. “I had an invite to play golf with Trump. Trump also walked me to my car. We still get the highest honour from the US administration,” Malay Mail Online quoted Najib as saying in parliament.