Faced with international sanctions and the potential threat of armed confrontation with the U.S., North Korean dictator Kim Jong Un consolidated power over the weekend by elevating his younger sister to a top political post.

On Saturday, Kim used a meeting of the ruling Workers’ Party’s key policy-making body, known as the Central Committee, to comment on ongoing tensions with Washington and announce several personnel changes, the KCNA news agency reported.

KCNA, Pyongyang’s official mouthpiece, said in an English report that Kim Yo Jong, the younger sister of North Korea’s ruler, was named as one of four elected alternate members of the politburo.

Kim Yo Jong and her brother are now the only millennials in the influential body; she is believed to have replaced her aunt, Kim Kyong Hui, who was a key decision maker during Kim Jong Il’s administration, Reuters said.

Kim Jong Il is the father of Kim Jong Un and Kim Yo Jong. The Kim family has been in power ever since Kim Il Sung founded the state in 1948.

Saturday’s appointment was a move by the current leader to ensure that his inner circle is full of trusted people, said Harry Kazanis, director of defense studies at the Center For the National Interest, an American think tank.

“Tensions with the United States are running as close to as an all time high, as you can imagine, so he’s going to want to continue consolidating power,” Kazanis told CNBC’s “The Rundown” on Monday. “He doesn’t want any danger of a coup or internal instability.”

Prior to the announcement of Kim’s appointment on Saturday, President Donald Trump issued yet another threat to the nuclear-armed nation. Years of diplomacy and financial incentives failed to sway the regime but “only one thing will work,” Trump said on Twitter, hinting at the prospect of military action.

Kim Yo Jong has long held senior positions in the Workers’ Party, with media reports previously referring to her as vice director of the propaganda department.

Her promotion is “part of a continual shake-up Kim Jong Un is doing,” Kazanis continued. “He doesn’t want to keep the same people his father had in place.”

In recent years, some immediate family members who might have been deemed threatening to the regime have been killed.

Kim Jong Un’s half-brother, Kim Jong-nam, who had publicly spoken out against the Kim family’s dynastic control, was assassinated in dramatic fashion last year, while the ruler’s uncle, Jang Song Thaek, was executed in 2013.