North Korea on Sunday celebrated leader Kim Jong-un's ascension to power two years ago and swore allegiance to him, state media reported, in the latest in a series of events staged to show that the young leader is firmly in charge after the execution of his uncle.

Kim took over as supreme commander of North Korea's armed forces on Dec. 30, 2011, shortly after his late father Kim Jong-il died. This year's anniversary came just weeks after Kim executed his powerful uncle Jang Song-thaek, prompting speculation of instability in Pyongyang's inner circle.

"The people's armed forces should hold higher the slogan of protecting comrade Kim Jong-un with our lives" and must move as if being one body according to Kim's order, said Choe Ryong-hae, the director of the military's political department, in a speech at the ceremony.

Choe is believed to be the second-most powerful man in the North after Jang's execution.

"Should the enemy leave even a speck of a mark on our land, we will wipe out all aggressors and achieve the historical mission of unification of the fatherland," Choe said, according to the North's Korean Central Television.

Choe also stressed that the North should put a top priority on moving the defense industry forward and should "ceaselessly modernize" the country's armament. But he made no mention of the country's nuclear weapons program.

Absent from the podium were Kim Kyong-hui, Jang's wife and aunt of leader Kim, and Kim Yang-kon, a Workers Party secretary for inter-Korean affairs.

Earlier, the military held a separate ceremony to pledge loyalty to the leader. (Yonhap News)