North Korean media are urging loyalty to leader Kim Jong Un as the country marks an important military anniversary on Thursday.

Kim Il Sung, the grandfather of the current leader, is said to have founded the Korean People's Revolutionary Army in the former Manchuria on April 25, 1932.

The ruling Workers' Party newspaper Rodong Sinmun carried a front-page editorial on Thursday calling for loyalty to the "supreme military commander, Kim Jong Un."

The article also shows a confrontational stance against the United States, saying the people and soldiers of North Korea are "smashing imperialism."

North Korean media are also emphasizing Kim's friendliness. State-run television is repeatedly airing a new song that praises Kim as a "friendly father."

The video shows soldiers, workers and medical staff in protective gear dancing and singing, as well as a TV announcer and her colleagues giving thumbs-up signs.

It also features a smiling Kim with children. The lyrics on screen call him "Kim Jong Un" without an honorific title.

Japan, the US and South Korea have expressed concern about Pyongyang's recent moves. On Monday, the North carried out firing drills involving what it calls "super-large rocket launchers." Observers say Pyongyang may soon launch additional military reconnaissance satellites.