The powerful sister of North Korean leader Kim Jong Un said her country will never see South Korea as a partner for diplomacy.

Kim Yo Jong, who is one of her brother’s top foreign policy officials, denounced the ongoing South Korea-US military drills as a “reckless invasion rehearsal” and claimed Seoul’s peace gestures conceal a “sinister intention” against Pyongyang, the North’s official Korean Central News Agency said.

On Monday, Kim Jong Un condemned the drills and vowed a rapid expansion of his nuclear forces as he inspected his most advanced warship.