North Korea has told the United States for the first time that it is prepared to discuss the denuclearization of the Korean Peninsula when North Korean leader Kim Jong Un meets President Donald Trump, a U.S. official said Sunday.

U.S. and North Korean officials have held secret contacts recently in which Pyongyang directly confirmed its willingness to hold the unprecedented summit, the official said on condition of anonymity.

The communications, still at a preliminary stage, have involved State Department officials talking to North Korea apparently through its United Nations mission, and intelligence officers from both sides using a separate back channel, the official said.