North Korea fires an intercontinental ballistic missile in this photo released by its state media on Nov. 19. Yonhap

North Korean leader Kim Jong-un declared a resolute nuclear response to threats by the United States during an on-site inspection of the country's test-firing of a Hwasong-17 intercontinental ballistic missile (ICBM) earlier this week, Pyongyang's state media said Saturday.

The missile, launched from Pyongyang International Airport, flew 999.2 kilometers for 4,135 seconds at an apogee of 6,040.9km and landed in the international waters of the East Sea, according to the Korean Central News Agency (KCNA).

"The test-fire clearly proved the reliability of the new major strategic weapon system to be representative of the DPRK's strategic forces and its powerful combat performance as the strongest strategic weapon in the world," it said in an English-language report. The DPRK is the acronym for the North's official name, the Democratic People's Republic of Korea.

It stressed that the firing was carried out under the "intolerable condition" that the "reckless military confrontational moves of the U.S. and other hostile forces" driving regional security to the "red line" have gone beyond the limit. It was referring to large-scale combined military drills recently staged by South Korea with some of key U.S. strategic assets mobilized.

Kim observed the test in person, along with senior North Korean officials, as well as "his beloved daughter and wife," it reported.

The KCNA released several photos that showed his daughter in a white winter jacket and black pants standing and walking together with Kim in front of the missile that sat on a launch truck. The daughter was also seen along with her mother, Ri Sol-ju, watching her father as he instructed military officials.

It marked her first official appearance in state media.

North Korea has never confirmed the existence of Kim's children. South Korean intelligence speculated Kim and his wife got married in 2009 and have two daughters and one son, born in 2010, 2013 and 2017, respectively.