Rodong Sinmun, the newspaper of the ruling communist party, said in an editorial that Kim "has always made his maximum efforts to bolster the military" against Washington.
"We will continue to give priority to the bolstering of the Korean People's Army... a mainstay of the military front against the imperialism," Rodong said in the dispatch monitored by Yonhap news agency.
Last Thursday the Stalinist state declared it had built nuclear weapons and was pulling out of six-nation talks aimed at ending a stand-off over its nuclear ambitions. Choe Thae-Bok, secretary of the Central Committee of the ruling Workers' Party, said Tuesday that the United States was seeking to "isolate and stifle" North Korea, KCNA said.
Military personnel danced at Jonsung Square in Pyongyang Tuesday night, singing songs praising Kim, KCNA said.
Fireworks, concerts, dancing performances and flower shows featuring Kimjongilia - a magnolia named after the North Korean leader - have been held across the country, according to KCNA.
Similar festive functions have taken place in Russia, Guinea, Senegal, Iran, Pakistan, Malaysia, Singapore and Nigeria, it said, in an apparent attempt to take the celebrations global.