North Korea’s young leader wants a state visit to China in the latest move in his push to lift the isolated state out of decades of poverty, but risks further fraying ties with his only powerful ally by sticking to the threat of a new nuclear test.

It is not clear whether China will be prepared to host him, as requested, in September when Beijing will be preoccupied with its own leadership change. The leadership may also have its doubts about the unproven Kim Jong-un, who, after only four months in office, defied his giant neighbour by conducting a long-range rocket test.

A source with ties to both Pyongyang and Beijing told Reuters on Friday that Mr. Kim’s uncle, Jang Song-thaek, effectively the second-most powerful figure in Pyongyang, had asked for the visit when he met Chinese leaders on a visit to Beijing last week.

“It will be a state visit. This was one of the most important missions of Jang Song-thaek’s visit,” the source said, speaking on condition of anonymity.

China’s foreign ministry declined to comment on the proposed visit, which would be Mr. Kim’s first trip abroad since he took office and became the third of his line to rule North Korea.

Mr. Kim, in his late 20s, appears to be trying hard to soften the dour image of his dictator father whom he succeeded in December.

He has appeared waving and smiling at public events, even attending a pop concert that included Disney characters, and at times – just as unusually for a North Korean leader – accompanied by his wife.

But for most of North Korea’s 22 million people, who are among Asia’s poorest, little has changed.

Some analysts see Mr. Jang as the driving force behind the North’s promise of economic reform. Mr. Kim’s uncle made his trip to China to press its leaders to provide greater backing for an economy brought to its knees by decades of mismanagement and international sanctions over missile and nuclear tests.

Beijing may be reluctant to host Mr. Kim in September at a time when China is preparing its own leadership change and because of the April rocket test, analysts said.

“North Korea has been nice to China only in the past 1 and a half months,” said Shi Yinhong, a professor of international relations at Renmin University in Beijing. “Heaven knows whether North Korea will change again in a few months.”

The proposed visit also comes when there are doubts over how willing Chinese companies are to put money in their neighbour, with its complex and contradictory investment laws.

One Chinese mining company this month took the rare step of turning to the Internet to air grievances over what it saw as the North’s unfair business practices.

Observers said new special enterprise zones in North Korea, aimed at building up business with China, have met with limited success.

United Nations estimates show that one-third of North Korea’s population is malnourished and it says the economy still has to regain output levels seen in the 1990s, when a devastating famine and the withdrawal of Soviet aid hit the country hard.

Chinese investment is the only viable large-scale option for the North.

“Jang Song-thaek went to China and discussed economic issues but the visit did not turn out to have the major impact that was expected. So Kim Jong-un will go to ask for the economic aid and long-term co-operation that they need,” said Yoo Ho-yeol, professor of North Korean studies at Korea University in Seoul.

China will expect to extract a price from Mr. Kim and will want the North to commit to return to talks with regional powers, so-called Six Party talks, aimed at defusing the nuclear threat on the Korean peninsula, Prof. Yoo said.

For the reclusive North, that nuclear threat has long been its only real diplomatic leverage with the outside world, especially the United States.

Mr. Kim’s father oversaw two nuclear tests and his long-range missile tests were seen by the United States as attempts to develop a ballistic missile capable of reaching the U.S. mainland.

While the most recent missile test in April went spectacularly wrong and saw sanctions tightened even further, the North is believed to be pushing ahead with plans to conduct a third nuclear test.

The source who disclosed Mr. Kim’s request for a visit said the North retained the capacity to carry out another test.