The White House has confirmed that U.S. President Donald Trump sent a letter to North Korean leader Kim Jong-un.

White House Press Secretary Sarah Sanders made the confirmation in a statement on Sunday, saying “correspondence between the two leaders has been ongoing.” 

However, she stopped short of elaborating when the letter was sent and what it said.

On Sunday, the North’s state media channel, Korean Central News Agency, said Kim received an “excellent” letter from Trump and that he will “seriously contemplate” its “interesting content.”

Trump apparently sent the letter as a response to one sent by Kim earlier this month.