Just over two weeks before President Donald Trump is due to meet his counterpart Xi Jinping in Beijing, Chinese uncertainty over the US leader's goals and the impact of the Iran war hang over the highly anticipated state visit.

Trump's trip, his first to China in his second term, is aimed at sealing a trade war truce the two leaders shook hands on when they met in South Korea in October.

But for Beijing, which likes to carefully choreograph such events to avoid any possibility of embarrassment, Trump's free-wheeling style is proving a challenge.

A source familiar with negotiations told AFP that Chinese officials were expecting more ambitious preparations for such a summit between the leaders of the rival superpowers.

The White House insisted however that preparations were going well for the visit from 31 March to 2 April, with regular contacts and interactions with Beijing.