North Korea has informed the U.S. in talks that it is willing to discuss denuclearization at an upcoming summit, a senior administration official confirmed Sunday.

“The United States and North Korea have been holding talks in preparation for a summit,” said the official, who spoke on condition of anonymity. The official also told The Washington Times that North Korea “has confirmed its willingness to talk about denuclearization.”

The message comes as the two countries prepare for a historic meeting between President Trump and North Korean leader Kim Jong-un, probably in May. A date and location for the summit haven’t been announced.

South Korean officials had told the U.S. weeks ago that North Korea was willing to discuss denuclearization with the Trump administration. But the development this weekend was the first time that U.S. officials heard the commitment directly from North Korea.

The U.S. official didn’t say when and how the U.S.-North Korea communications had taken place. But the two sides had held multiple direct contacts, Reuters reported.

Central Intelligence Agency Director Mike Pompeo and a team at the CIA have been working through intelligence back-channels to make preparations for the summit, CNN reported, citing administration officials. The report said U.S. and North Korean intelligence officials have spoken several times and have even met in a third country, with a focus on agreeing on a location for the talks.

It’s not clear how North Korea defines “denuclearization,” although the Trump administration has said Pyongyang must abandon its nuclear weapons program. North Korea has pushed for the U.S. to remove its troops from the Korean peninsula as part of any agreement.