Park Chung-hee seized power in a 1961 coup d'état and ruled as a military strongman until his election and inauguration as the President of the Third Republic of South Korea in 1963. The attack at the Blue House took place in the context of the Korean DMZ Conflict (1966–69), which in turn was influenced by the Vietnam War.
Following the 1967 South Korean presidential election and the legislative election, the North Korean leadership concluded that Park Chung Hee's domestic opposition no longer constituted a serious challenge to his rule. On June 28 – July 3, the Central Committee of the Workers' Party of Korea held an extended plenum at which North Korean leader Kim Il-sung called on the cadres "to prepare to give assistance to the struggle of our South Korean brethren." In July 1967, a special squad of the recently established Unit 124 of the Korean People's Army (KPA) was entrusted with the task of assassinating Park. This decision was probably facilitated by the fact that in 1967, the Vietnam War entered a new stage of escalation, under which circumstances the U.S. military forces, preoccupied as they were with Vietnam, could not easily take retaliatory measures against North Korea. In 1965–1968, North Korea-North Vietnam relations were very close, and the DPRK provided substantial military and economic assistance to North Vietnam. North Korean propaganda sought to depict the post-1966 commando raids as a South Korean guerrilla movement akin to the Viet Cong.
Thirty-one men were handpicked from the elite all-officer KPA Unit 124. This special operation commando unit trained for two years and spent their final 15 days rehearsing action on the objective in a full-scale mockup of the Blue House.
These specially selected men were trained in infiltration and exfiltration techniques, weaponry, navigation, airborne operations, amphibious infiltration, hand-to-hand combat (with emphasis on knife fighting), and concealment.
As Kim Shin-Jo, the only known surviving commando, stated, "It made us fearless—no one would think to look for us in a graveyard." Their training was rigorous and often in adverse conditions, such as running at a speed of 13 km/h (8 mph) with 30 kg (66 pound) rucksacks over broken and unforgiving terrain, which sometimes resulted in injuries such as lost toes and feet from frostbite.