President Donald Trump in the Oval Office Mark Wilson | Getty Images

After Donald Trump's flip-flop on the one-China policy during his phone call with Chinese President Xi Jinping early this month, the next big question for diplomatic pundits is when and where the two leaders will meet in person. Several Chinese sources said suggestions have been made that the first meeting between the two leaders will be on the sidelines of the G20 summit in Germany in July. "Beijing is in contact with Trump's team over the possibility of a bilateral meeting on the sidelines of the G20 summit in Hamburg in July," one of the sources said, adding that Washington had also expressed similar intentions. More from the South China Morning Post:

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Diplomatic pundits also believe the G20 summit is likely to be the first opportunity for Xi and Trump to meet, even though there are still uncertainties over whether the US president will attend as his new administration appears sceptical of multinational political gatherings. Yuan Peng, vice-president of the China Institute of Contemporary International Relations, said a personal meeting between the two leaders would be essential to set the tone and direction for their relationship and to establish new ways of communication. "This is the most urgent thing for both countries to work at in the near future," he said.

James Woolsey, a former CIA director who served as Trump's senior adviser on national security until last month, also believes the G20 would be a good time for the leaders to get together at an early date. "The key is to not get bogged down in rhetoric, but to start working together on getting things done," he said. Dr Gal Luft, the co-director of the Washington-based Institute for the Analysis of Global Security, said both leaders should meet as soon as possible "to establish personal bonds and learn to know each other". "I would argue that the first five minutes of the meeting is the most critical part because we are dealing with two alpha males here. They need to understand each other, but more important, like each other," Luft said. "Personal chemistry that will emerge, or not, from this will define the relationship and I cannot over emphasise this point. If they like each other, they can do business together and call each other when things are not right. But if the chemistry is not that good, then the relationship will develop in a totally different trajectory," he said. If Trump chooses to skip the Hamburg G20 summit, the most likely opportunity for a meeting between the two leaders would be the annual Asia-Pacific Economic Cooperation summit in Vietnam later this year.

Yuan at the China Institute of Contemporary International Relations said: "[It] largely depends on Trump because we have made it very clear that our leader will attend both G20 and Apec. As long as Trump shows up, we will try our best to arrange bilateral talks for the leaders." A July meeting with Trump would be of special significance for Xi because the Chinese leader is eager to show a steady relationship with the US as intense jockeying for power is underway ahead of this autumn's Chinese Communist Party congress in Beijing, according to observers. China is also organising an One Belt, One Road summit in May to promote its international trade initiative , but it is unlikely Trump himself will attend. Steve Tsang, the director of the London-based SOAS China Institute, said if that if there were no major incidents or mishaps in US-China relations between now and the G20 meeting in the summer, a Xi-Trump meeting would be "a very positive development for both, particularly for Xi in preparation to the 19th Party Congress.". But this was still a big "if" at the moment, he cautioned. "We are many months away from the Hamburg summit. Will Trump leave his rather strong and worrying campaign promises over China alone in the meantime? No one knows," he said. Yuan admitted that the lack of effective communication channels with Trump's team remains Beijing's biggest challenge in handling ties with the new administration, noting that the US president appears to show little interest in using existing channels to manage diplomatic, military and economic relations.

"All of a sudden, if something happens, who do we contact? That's the biggest risk in the next few months. So my suggestion is for two top leaders to find some ways to meet as soon as possible because both Trump and Xi are quite unique and strong leaders," he said. Yuan added that Beijing and Washington should also try to find new areas of cooperation, suggesting Xi invite Trump to join the China-led Asian Infrastructure Investment Bank and also take part in the One Belt, One Road trade initiative. Former CIA director Woolsey also believes the trade project offers an opportunity for China and the US to begin working together on mutually beneficial initiatives, such as financing and building infrastructure schemes. "If we can somehow get the people from the two governments ... into a world in which they are working together to start to get things built, a lot of the agonies will go away, or at least be damped down," he said. Apart from official channels, both sides need to find ways to establish informal means of communication, analysts suggested.