U.S. President Donald Trump suggested Thursday that Chinese President Xi Jinping ought to meet personally with pro-democracy protesters in Hong Kong to resolve 10 weeks of demonstrations against Beijing's control of the semi-autonomous territory.

The U.S. leader, whose own motorcades often avoid driving past protests against him, said on Twitter that if Xi meets with the mostly youthful demonstrators "there would be a happy and enlightened ending to the Hong Kong problem. I have no doubt!"

Trump said, "I know President Xi of China very well. He is a great leader who very much has the respect of his people. He is also a good man in a 'tough business.' I have ZERO doubt that if President Xi wants to quickly and humanely solve the Hong Kong problem, he can do it. Personal meeting?"

The Chinese government has given no indication that Xi is planning to visit Hong Kong. Chinese security forces have been spotted conducting exercises in Mainland China, just across the border from Hong Kong, although there has been no troop movement toward Hong Kong.

China's ambassador to London, Liu Xiaoming, warned Thursday that Beijing will not "sit by and watch" the protests mount. The envoy said Beijing is ready to "quell the unrest swiftly" if the crisis in Hong Kong becomes "uncontrollable."

The U.S. and China, the world's two biggest economies, are in the midst of contentious, drawn-out trade negotiations. But Trump suggested any trade resolution can be delayed as long as the Hong Kong protests on the streets and this week at Hong Kong's international airport continue.

Trump went on Twitter late Wednesday to boast that his administration has the upper hand against Beijing in the trade negotiations. After writing that "thousands of companies" are leaving China, the president said, "Of course China wants to make a deal. Let them deal humanely with Hong Kong first!"

The president's tweets were his most extensive about the crisis in the Chinese territory since the demonstrations broke out. In remarks to reporters Tuesday, Trump, who last week took a hands-off stance on the protests, said the Hong Kong situation "is a very tough situation, very tough. We'll see what happens, but I'm sure it will work out." He expressed the hope that no one would get hurt and "for liberty."