Kim Yo Jong has been described as a mouthpiece for her brother, North Korean leader Kim Jong Un — and a potential successor.

In a statement carried by state media, Kim Yo Jong said she doesn’t deny the personal relationship between her brother and Trump “is not bad.” But she said if their personal relations are to serve the purpose of North Korea’s denuclearization, North Korea would view it as “nothing but a mockery.”

North Korea has ​doubled down on expanding its nuclear fleet and continued its criticism of the U.S., although it has refrained from personal attacks on Trump.