Relations with China have slowly deteriorated in the past year over Pyongyang's ongoing nuclear tests.
Despite the pro-nuclear rhetoric, Kim's speech was also heavily focused on the economy, which has proven surprisingly resilient despite being heavily targeted by USA and global sanctions. "Policy didn't work!" Trump tweeted early on Monday morning.
"The reason why North Korea suddenly hosted the meeting is because it felt threatened by the global community's unprecedentedly tough sanctions, following its sixth nuclear experiment in September", said Chung Sung-jang, director of unification strategy studies at the Sejong Institute. The experiment triggered the United Nations Security Council to impose a ban on North Korea's lucrative textile exports and a chain reaction among the global community to cut off diplomatic and economic ties with the rogue regime. Kim Yo Jong, although not be as powerful as her older brother, directs many major events and demands the respect of other officials.
Anton Morozov, a Russian lawmaker who recently returned to Moscow after a visit to Pyongyang, said the regime informed him of the test while showing him calculations that prove the weapon can range the US West Coast.
According to a report in The Washington Post, she was promoted at a meeting of senior party members as North Korea celebrated the 20th anniversary of Kim Jong-il accepting the title of general secretary of the ruling Worker's Party of Korea.
The threat came after Donald Trump said he would "totally destroy" North Korea during a speech to the United Nations (UN).
North Korea has been accusing the USA and South Korea of developing a plot named as "Plan Jupiter" a biochemical operation created to dethrone Kim, Newsweekreported.
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 previous year , while the ruler's uncle, Jang Song Thaek, was executed in 2013.
Kim Yo Jong's new job will be as an alternative member of the Central Committee - the chief decision-making body over which Kim presides. She also said to have studied computer science at Kim Il-sung University where it is believed that she studied alongside Kim Eun-gyong, the daughter of Japanese abductee Megumi Yokota.
His comments were made hours before Trump tweeted that "only one thing will work" in dealing with Pyongyang following years of dialogue that the USA president said had failed to deliver results.
The Guardian reported that Michael Madden said: "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".
She is blacklisted by the U.S. over alleged links to human rights abuses in North Korea.
A North Korean known only as "Kim" was allegedly paid to carry out an attack with biochemical substances but was foiled, a statement by the North Korean ministry of state security said. "Even if he has informal or off-the-record meetings, Ri's interlocutors can be assured that whatever proposals they proffer will be taken directly to the top". Tensions over North Korea's weapons programme have soared in recent months with Pyongyang launching a flurry of missiles.