Beijing: Donald Trump toured the Forbidden City with Chinese leader Xi Jinping on Wednesday as the US president began the crucial leg of an Asian trip intended to build a global front against North Korea's nuclear threats.
After warning the North's "cruel dictatorship" in a speech in Seoul against testing the United States, Trump and First Lady Melania Trump were met by Xi and his wife Peng Liyuan for tea at the former imperial palace.
The genial gathering will be followed on Thursday by a full day of thorny talks, with Trump looking to prod Xi into doing more to squeeze North Korea economically and to address China's massive trade surplus with the United States.
The Trump administration sees Beijing as the key to controlling Pyongyang, which depends on China for its economic survival and for 90 percent of its trade.
Earlier, Trump congratulated Xi on his reappointment as China's Communist Party chief, tweeting: "I very much look forward to meeting with President Xi who is just off his great political victory."
Trump's use of the term "political victory" for the outcome of last month's Communist Party congress was seen by analysts as a conciliatory move before tough talks.
"He's laying it on thick to put Xi in a good mood because he will have unpleasant things to tell him," said Jean-Pierre Cabestan, China politics specialist at Hong Kong Baptist University.
Xi has prepared an extravagant "state visit-plus" for Trump, who was greeted by children waving US and Chinese flags at the airport. He was treated to a Peking Opera performance at the Forbidden City.
Xi said during the Forbidden City tour that he expected Trump's visit to yield "positive and important" results.
Trump later posted his first messages on Twitter since arriving China, breaking through the country's "Great Firewall" which blocks the social media website.
"THANK YOU for the beautiful welcome China!
"North Korea is not the paradise your grandfather envisioned. It is a hell that no person deserves."
"Yet despite every crime you have committed against God and man, we will offer a path towards a much better future."
It would have to begin, though, with the North stopping ballistic missile development, Trump said, and "complete verifiable and total denuclearisation".