Trump says Kim Jong-un's attitude changed after his second visit to China
US President Donald Trump has said there is a "very substantial chance" a historic summit with North Korea's Kim Jong-un next month may not happen.
He said the North must meet conditions for the summit to go ahead though if it did not, it might happen "later". Mr Trump was speaking as he received South Korea's President Moon Jae-in at the White House.
The North has said it may cancel the summit if the US insists on it giving up nuclear weapons unilaterally.