North Korean leader Kim Jong Un revealed his daughter to the world for the first time on Saturday in striking photos showing the pair hand-in-hand before the launch of the nuclear-armed country's largest ballistic missile the day before.

North Korea test-fired a Hwasong-17 intercontinental ballistic missile (ICBM) on Friday, state news agency KCNA reported on Saturday.

A surprising addition to the launch was the presence of Kim's daughter, whose existence had never been publicly confirmed before. Her unexpected appearance raises the prospect that leadership of the totalitarian state could pass to a fourth generation of Kims, and suggests that nuclear weapons will be part of that inheritance, analysts said.

KCNA did not name the girl, who is seen in photographs in a white puffy coat holding hands with her father as they looked at the massive missile.

"This is the first observed occasion where we have seen Kim Jong Un's daughter at a public event,” said Michael Madden, a North Korea leadership expert at the U.S.-based Stimson Center.

“It is highly significant and represents a certain degree of comfort on Kim Jong Un's part that he would bring her out in public in such fashion.”

Jenny Town of 38 North, a Washington-based North Korea research organisation, said that Kim's taking his daughter to an ICBM test and publishing pictures of the two of them watching the launch suggests he is not about to bow to pressure to slow his weapons programmes or return to negotiations.

That has the gravity of handing down a legacy, she said. These optics give the sense that these are part of her legacy too now.

SUCCESSOR IN WAITING?

Kim is believed to have as many as three children, two girls and a boy, experts said.

Some observers believed one of those children was seen in footage of celebrations for a national holiday in September. In 2013 retired American basketball star Dennis Rodman said Kim had a“baby” daughter named Ju Ae.

After a trip to North Korea that year, Rodman told The Guardian newspaper he had spent time with Kim and his family, and held the baby.

Ju Ae is estimated to be about 12-13 years old, which means that in four to five years she will be preparing to attend university or go into military service, Madden said. "This would indicate that she will be educated and trained to go into leadership - it could be preparing for her to assume the central leader's position, or she could become an adviser and behind-the-scenes player like her aunt,” he said.

North Korea has never announced who would follow Kim if he is incapacitated, and with few details known about his children, analysts had speculated that his sister and loyalists could form a regency until a successor is old enough to take over.

The appearance of the leader's daughter at this event could suggest fourth-generation hereditary succession, Madden added. ”Her presence is for an elite audience,” he said.

Kim's wife, Ri Sol Ju, also made a rare appearance at Friday's launch, according to KCNA. ”Whenever Ri Sol Ju appears, there is strategic messaging involved. Normally designed to tamp down tensions, counter other aggressive messaging (like tests), or show Kim family cohesion in times of internal troubles,” said Ken Gause, a North Korea leadership expert with CNA, a U.S.-based non-profit research organization.

Her presence also fits a trend of Kim“normalising” politics inside the regime and the dynamics around his position as supreme leader, Gause added.