US President Donald Trump said on Saturday he was open to a trade deal with Chinese President Xi Jinping that would be 'monumental', as they began high-stake talks that could ease tensions or plunge the world's two largest economies into a deeper trade war. 'I actually think that we were very close and then something happened where it slipped a little bit and now we're getting a little bit closer,' Trump said on the sidelines of the Group of 20 (G20) meeting in Osaka, western Japan. 'But it would be historic if we could do a fair trade deal. We're totally open to it and you're totally open to it,' he said. 'I think this will be a very productive meeting and I think we can go on to do something that truly will be monumental,' he added.