A photo exhibition held by North Korea in Pyongyang, April 24, to celebrate the 90th founding anniversary of the Korean People's Revolutionary Army, which falls April 25, is seen in this photo released by the Korean Central News Agency. Yonhap

North Korea held a military parade in Pyongyang, Monday evening, to mark a key national anniversary, an informed source said, in what was seen as a highly choreographed event to cement internal unity and highlight its military heft.

The North kicked off the parade at Kim Il Sung Square at 10 p.m. on the 90th founding anniversary of the Korean People's Revolutionary Army (KPRA), according to the source.

It was not immediately known whether the current leader, Kim Jong-un, attended the parade.

In the run-up to the event, satellite imagery had shown the North mobilizing thousands of troops and key pieces of military equipment in apparent rehearsals ― a sign the parade could be a large-scale display of its military clout.

Observers said Pyongyang could bring up to 20,000 troops for the parade and flaunt its newest strategic weapons, such as the Hwasong-17 ICBM, the Hwasong-8 hypersonic missile and a guided weapon carrying a tactical nuclear warhead.

North Korean students hold a ball at an outdoor plaza in Pyongyang, April 25, to celebrate the 90th founding anniversary of the Korean People's Revolutionary Army, in this screen capture from footage supplied by the Korean Central Broadcasting Station. Yonhap

The military aspect aside, the North could liven up the festive mood through fireworks and colorful lights so as to imbue citizens ― still reeling from persistent economic travails and pandemic-driven restrictions ― with a sense of national pride.

Monday's parade was initially expected to begin at the start of Monday, but it did not proceed amid a forecast of rainfall.

It marks the North's first military parade to celebrate the KPRA anniversary under the leadership of Kim, who took power about a decade ago.

The North has usually held such a parade on the anniversary of the birth of national founder Kim Il-sung, April 15, the founding anniversary of the ruling Workers' Party, Oct. 10, or the nation's foundation day, Sept. 9.

Analysts said Kim might have chosen the KPRA founding anniversary to emphasize his family's illustrious pedigree based on his grandfather's colonial-era fight against Japan to help solidify his legitimacy.

Hours before the parade, the North's state media, including the official Korean Central News Agency (KCNA), carried articles on the anniversary.

In an editorial, the North's main newspaper, the Rodong Sinmun, instead urged all people and the country's armed forces to devote their "absolute loyalty" to leader Kim.

"We must more thoroughly establish the revolutionary discipline and order, in which the party, nation and the people move in unity under the leadership of the central party with the ideologies and intentions of our respected and beloved general secretary boiling within our hearts," it said.

The North usually marks every fifth and 10th political anniversaries with large-scale celebrations.

Under Kim's rule, the North has held 12 major military parades for national celebrations, including this week's event. (Yonhap)