A photo released by the official North Korean Central News Agency (KCNA) shows North Korean leader Kim Jong-un, accompanied by his daughter during the test firing of a new type of intercontinental ballistic missile (ICBM) Hwasongpho-17 at Pyongyang International airport in Pyongyang, North Korea, Nov. 18. EPA-Yonhap

The daughter of North Korean leader Kim Jong-un who was recently seen in public for the first time at a missile launch site is his second child, South Korea's spy agency told lawmakers Tuesday, as speculation swirled about his motives for bringing her to the attention of the outside world.

On Saturday, North Korea said that Kim observed the launch of the country's most powerful intercontinental ballistic missile ― Hwasong-17 ― the previous day with his wife Ri Sol-ju and their ''beloved daughter.'' State media released photos showing Kim walking hand-in-hand with a young girl clad in a white coat and red shoes past a massive missile placed on a launch truck, and watching a soaring weapon from a distance.

In a closed-door briefing at a parliament committee, South Korea's National Intelligence Service, the country's main spy agency, told lawmakers that it assesses the daughter is Kim's second child named Ju-ae, Yoo Sang-bum, one of the lawmakers who attended the meeting, said.

Youn Kun-young, who also attended the NIS briefing, confirmed the substance of Yoo's comments but refused to provide further details.