North Korea's Supreme Leader Kim Jong-un has given his sister more power by promoting her to the nation's top decision-making body.
Kim Yo-jong, the youngest daughter of late leader Kim Jong-il, will be replacing her aunt as a member of the Workers Party's Politburo.
Ms Kim, 30, was referred to as a senior party official three years ago.
The Kim family has ruled North Korea since the country was established following the Second World War in 1948.
Ms Kim, who has frequently appeared alongside her brother in public and is thought to have been responsible for his public image, was already influential as vice-director of the propaganda and agitation department.
She is blacklisted by the US over alleged links to human rights abuses in North Korea.
Her promotion was announced by Mr Kim at a party meeting on Saturday as part of a reshuffle involving dozens of other top officials.
When Ms Kim was given a key post at the country's rare ruling party congress last year, it was widely expected that she would take up an important role in the country's core leadership.
Who is Kim Yo-jong?
Among other announcements made on Saturday was the decision to promote Foreign Minister Ri Yong-ho - who last month referred to US President Donald Trump as "President Evil" at a UN meeting - to a full vote-carrying member of the Politburo.
Mr Ri has recently accused Mr Trump of declaring war on North Korea and said that if the president continues with his "dangerous" rhetoric the US will become an "inevitable" target for missile strikes.
The promotions come as a defiant Mr Kim once again made it clear that North Korea's nuclear weapons programme would continue despite sanctions and threats.
His comments were made hours before Mr Trump tweeted that "only one thing will work" in dealing with Pyongyang following years of dialogue that the US president said had failed to deliver results.
North Korea's missile programme
Can the US defend itself against North Korea?
Inside the world's most secretive country