Trump finally gave the U.S. seal of approval to a long-standing South Korean ambition: joining the elite club of nations operating SSNs. Washington had repeatedly resisted Seoul’s requests, however, citing non-proliferation constraints and the political sensitivity of transferring nuclear-propulsion technology.

Donald Trump is now back on Air Force One and flying home. His talks with Chinese President Xi Jinping lasted for about 90 minutes - with reporters told that he'd score their meeting "12 out of 10".

“There is nothing like this in the world in terms of the speed and the depth of the movement of this unmanned vehicle — and it is unlikely there ever will be,” he said.