North Korean leader Kim Jong Un has delegated some of his power to his sister, Kim Yo Jong, and she now serves as his “de facto second-in-command” of the isolated country, South Korean intelligence has said.

“Kim Yo Jong, the first vice department director of the Workers’ Party Central Committee, is steering overall state affairs based on the delegation,” the National Intelligence Service said Thursday during a closed-door meeting with South Korean lawmakers. The goal of the power shift is to "relieve (Kim's) stress from his reign and avert culpability in the event of policy failure.”

“Chairman Kim Jong Un is still maintaining his absolute authority, but some of it has been handed over little by little,” the agency continued.

Kim Yo Jong has not been officially designated as his successor.

A few other top-ranking North Korean officials have also been charged with steering the country’s economy. The ruling Workers’ Party admitted Thursday that the country faces serious economic challenges.

In a statement that ran on state media, the Party admitted that “the economy has not been improved in the face of sustained severe internal and external situations and unexpected manifold challenges, with the result that the goals to be attained for national economic growth have been seriously delayed and the people's living standards have not been improved remarkably.”

U.S.-led sanctions, along with the coronavirus, are two reasons why economic growth is lagging. North Korea and the U.S. have failed to reach a nuclear deal that would lift some of the sanctions, frustrating Pyongyang.

Kim Jong Un is expected to unveil a new foreign policy agenda next year, following elections in the United States. President Trump has called Kim Jong Un “a friend,” but Democratic nominee Joe Biden has said he would take a tougher line on Pyongyang if he wins the presidency.

Trump has previously claimed that he would make deals “very quickly” with North Korea if he is reelected in November.