Donald and Melania Trump hosted China's Xi Jinping and his wife at the White House on Friday, capping off what the President called a 'tremendous visit from two spectacular people.'

But before the quartet could sit down for tea, Trump was hammered by a brutal question as they posed for photos on the South Portico.

'Mr President, did you call on President Xi to stop buying oil from Iran?' the reporter asked.

Trump and Xi stared straight ahead as they stood abreast, neither betraying anything on their poker faces. 

The question cut to the heart of the tension between the two leaders. Xi has resisted months of pressure from Trump to lean on Tehran to end the almost seven-month war. 

Beijing buys more than 80 percent of Iran's seaborne oil exports and is an indispensable customer for the sanctioned regime. 

Trump and Xi later sat down for tea and addressed reporters, speaking in glowing terms despite the lingering geopolitical issues between the two superpowers.

'I see a brighter China-US future,' Xi told reporters, describing his Washington, DC, visit - the first in 11 years - as highly successful.

Trump claimed that they had 'made tremendous strides' and that 'our farmers are going to be very happy.' 

But so far the only concrete new outcome publicly disclosed from the summit is an agreement to extend a trade truce that was set to expire November 10 by two months. 

It is unclear what Trump meant when he referred to farmers, but Beijing has previously pledged to buy at least $17 billion a year in agricultural goods through 2028, alongside a separate commitment to purchase 25 million metric tons of US soybeans annually.

Xi wants Washington to halt arms sales to Taiwan, the self-governing democratic island off China's southeast coast, which Beijing claims as its own.

The AI race has made Taiwan an even bigger prize: the island makes around 90 percent of the world's most advanced chips. 

After their White House tea, Trump and Melania are set to accompany Xi and his wife, Peng Liyuan, to the National Archives for the final event of the Chinese leader's three-day state visit.

The four were expected to view historic documents, including America's founding texts, in a carefully choreographed symbolic end to the summit.

Xi and his wife will return to the presidential airport, Joint Base Andrews, in Maryland for their flight home later today.