North Korean leader Kim Jong-un has elevated his sister, Kim Yo-jong, to an alternate member of the politburo – the top decision-making body over which Kim Jong-un presides.

Alongside Kim himself, the promotion makes Kim Yo-jong the only other millennial member of the influential body.

Her promotion indicates the 28-year-old has become a replacement for Kim’s aunt, Kim Kyong-hee, who had been a key decision maker when former leader Kim Jong-il was alive.

“It shows that her portfolio and writ is far more substantive than previously believed and it is a further consolidation of the Kim family’s power,” said Michael Madden, a North Korea expert at Johns Hopkins University’s 38 North website.

In January, the US Treasury blacklisted Kim Yo-jong along with other North Korean officials over “severe human rights abuses”.

The promotion was one of several Kim announced in a speech to a meeting of the powerful Central Committee of the ruling Workers’ Party on Saturday, according to state media on Sunday.

Kim Jong-sik and Ri Pyong-chol, two of the three men behind Kim’s banned rocket program, and foreign minister Ri Yong-ho were also promoted.

Ri, who named Donald Trump “President Evil” in a bombastic speech to the UN General Assembly last month, was promoted to full vote-carrying member of the politburo.

In the speech, Kim also said his nuclear weapons were a “powerful deterrent” which guaranteed North Korea’s sovereignty, state media reported on Sunday, hours after US President Donald Trump said “only one thing will work” in dealing with the isolated country.

Trump did not make clear to what he was referring, but his comments seemed to be a further suggestion that military action was on his mind.