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The Second Korean War

By Mitchell Lerner

Beginning in late 1966, a series of small conflicts erupted on the Korean Peninsula for the first time since the Korean War. With the deployment of guerillas into South Korea for the first time since the Korean War, the contentious period of violence became to be known as the “Second Korean War.”

Table of Contents


In late 1966, North Korean leader Kim Il Sung began sending guerrillas into South Korea for the first time since the Korean War, setting off a three-year conflict known as the “Second Korean War.” Although no large-scale battles were fought during this period, smaller military incidents grew significantly, increasing from 42 in 1965 to 286 in just the first six months of 1967. The tensions reached a peak in January 1968 when the DPRK launched an assassination attempt against ROK President Park Chung Hee that narrowly missed, and then captured the American spy ship Pueblo, leaving 82 American sailors in DPRK prison camps for almost a year. Both North and South Korea, and many of their allies, thought the possibility of a conventional war was high, and it took pressure from both the United States and the Soviet Union to restrain the leadership of both countries throughout these tense years. In the end, these conflicts left hundreds dead on both sides before the North suddenly stopped its attacks in 1969. Although the causes of Kim’s belligerency are still in question, its legacy was, among other things, to solidify the relationship between the United States and South Korea, while driving a wedge between the Soviet Union and the North.


On July 27, 1953, American Army Lieutenant General William Harrison Jr. and North Korean General Nam Il signed an armistice agreement in Panmunjom, ending the military conflict that had ravaged Korea for three years. Although no official peace agreement was signed, the tensions on the Korean Peninsula nevertheless declined quickly, and while hostilities still erupted on occasion, the overall level of violence declined dramatically. The calm, however, swiftly faded in the late-1960s, as North Korea launched a new wave of aggression against the South and its allies. Although never exploding the way the conflict had in 1950, this “Second Korean War” again turned the world’s attention to the region, and left a wake of destruction and hostility that hardened the contours of the Korean division.

Violence Erupts

The explosion of violence started in late 1966, when Kim began sending guerrillas into South Korea for the first time since the Korean War. The relative stability along the DMZ was soon shattered. Military incidents grew from 42 in 1965 to 286 in just the first 6 months of 1967, and by late 1967, mutual exchanges of gunfire across the armistice line had become a daily event. ("Telegram From the Commander in Chief, United Nations Command, Korea and the Commander of United States Forces, Korea (Bonesteel) to the Commander in Chief, Pacific (Sharp)," July 21, 1967, Lyndon B. Johnson Presidential Library (henceforth "LBJL"), National Security File, Country File, Korea, Vol. IV.)

"Never," wrote the East German Ambassador to North Korea as 1967 drew to a close, "since the end of the Korean War, have there been so many and such severe incidents at the armistice line as in 1967." (Letter from GDR Ambassador to DPRK, December 8, 1967, to State Secretary and First Deputy Minister of Foreign Affairs, Ministerium fur Auswärtige Angelegenheiten der DDR [Ministry for Foreign Affairs of the GDR, in Mitchell Lerner, “Mostly Propaganda by Nature,” NKIDP Working Paper #3. )

Direct attacks on US property were not uncommon; one attack, in May 1967, resulted in the destruction of two US infantry barracks, killing two men and leaving 19 wounded. ("Security Conditions in South Korea," CIA report, June 23, 1967, LBJL, National Security File, Country File, Korea, Vol. IV.) That year also saw two ship-to-shore firefights along the Southern coast, a North Korean attack on a ROK army barracks, and large-scale guerrilla infiltration. American troops assigned to South Korea routinely found their tours of duty extended to meet the growing danger, and the U.S Joint Chiefs of Staff quietly re-classified the northern part of South Korea as a hostile fire zone, making troops stationed there eligible for combat pay, as well as for the Combat Infantryman Badge and Combat Medical Badge. DPRK propaganda stressed American responsibility for the provocations, but even their allies knew who was responsible for the outbreaks; Soviet officials in North Korea, according to one report, "held the view that they were mostly instigated by the DPRK." (Letter to Secretary of State and First Deputy Minister of Foreign Affairs Comrade Hegen, from Embassy of the GDR in the DPRK, December 12, 1966, Archives of the Foreign Office, Berlin, in Lerner, “Mostly Propaganda by Nature.” )

The Blue House Raid

The North’s aggression reached a peak in 1968. On January 17, thirty-one North Korean Army officers snuck across the DMZ into South Korea. The soldiers were part of the 124th Special Forces, an elite commando unit that had been trained extensively in weapons and martial arts, now charged with a mission to assassinate ROK President Park Chung Hee. After completing their mission, they were told, other units would follow them, taking over ROK installations, freeing prisoners, and spreading propaganda to the population. Shortly after crossing into the South, the soldiers were spotted by a group of loggers. They detained the men but decided not to kill them, and instead continued South on their mission. The loggers, however, alerted local authorities to the encounter, leaving Seoul on high alert. On January 21, while disguised as ROK soldiers, the North Korean soldiers reached the "Blue House," the official presidential residence in Seoul, each carrying automatic rifles, 320 rounds of ammunition, 14 grenades, pistols and knives. As they approached the Blue House, however, a suspicious ROK policeman stopped them shortly before they could attack, and the ensuing firefight saw eight South Koreans and five members of the commando team killed. The rest of the guerrillas fled, sparking a nationwide manhunt that left all but one of the intruders dead, along with 68 South Koreans and three Americans.

An infuriated ROK population demanded retaliation. The Korean Peoples Anti-Communist League sponsored a rally in Seoul; despite twenty-degree weather, 100,000 people showed up to march three miles and burn a ten-foot straw effigy of North Korean leader Kim Il Sung. Similar feelings were echoed across the nation. Anti-DPRK sentiment, wrote the Czech embassy to Pyongyang, was so strong that "South Korean authorities did not even have to apply direct pressure to ensure participation in these demonstrations." ("Pueblo and American-South Korean relations," February 9, 1968, Political Report #11, Czech Embassy in the DPRK, Report # 031/68, SM-021712/68, in Lerner, “Mostly Propaganda by Nature.”) When ROK President Park Chung Hee, in response, ordered the creation of a local defense force to supplement the regular army, 2 million South Koreans volunteered within six months. Under fierce American pressure, Park managed to restrain his military from taking major retaliatory actions against the North, but it was not easy. "Few people" recalled one American general, "realize how close we came to war on January 21." ( New York Times, August 16, 1968.)

USS Pueblo Incident

War seemed even more likely a few days later. On January 23, North Korean air and naval forces surrounded the USS Pueblo, an American spy ship operating off the DPRK coast in the Sea of Japan. "Heave to," one of the ships ordered, "or I will open fire." Pueblo had been warned to expect some routine harassment, and Captain Pete Bucher confidently raised his ship's signal flags: "I am in international waters. Intend to remain in the area until tomorrow." Suddenly, a North Korean P-4 torpedo boat backed down on the American ship, with an armed landing party set to board Pueblo. The spy ship's engines slipped into gear at the last moment, but escape proved impossible. The faster DPRK ships again closed on Pueblo, and soon opened fire. With his ship virtually unarmed, and with no support on the horizon, Bucher surrendered, with one man dead and numerous others injured. Pueblo was boarded and sailed into Wonsan Harbor. The crewmen were violently dragged onto land and bused to a North Korean prison camp, where they were held for eleven months of torture, abuse, and public humiliation.

This time it was the American public that demanded retaliation, especially as the DPRK regularly used the Pueblo men as propaganda pawns throughout the year. Senator Russell Long (D-LA) suggested the United States begin sinking North Korean gunboats and holding their merchant ships hostage; "If the Soviets want to deal itself in on it," Long trumpeted, "they can get in on it, too." (Philadelphia Enquirer, January 29, 1968.)Telegrams flooded the White House. One from Los Angeles asked Johnson to "drop a juicy bomb on their capital" and another from Philadelphia demanded, "drop the hydrogen bomb and let's end it." (Los Angeles telegram from Irving Pell, Philadelphia telegram from Herbert Trulick, in LBJL, White House Central Files, subject file, defense, ND 19/CO 151, box 210. )

South Korea continued its demand for a response as well. In February, over 1,000 ROK high school students protested in front of US Information Service Centers at Taegu and Kwangju, demanding action against the North and an end to "boot-licking conferences." ("Chronology of Diplomatic Activity in Pueblo Crisis," U.S. State Dept. report, April 29, 1968, Declassified Document Record System, document #CK3100150473, p. 298. )One ROK newspaper blasted the "humiliating appeasement posture of the United States," and another concluded, "Instead of dealing a severe blow of retaliation against a series of barbarous acts of bellicosity committed by the North Korean communist aggressors, the world's biggest power seems to have started dancing to the communist propaganda tune." ("Humiliating appeasement" in telegram 4015 from American Embassy Seoul to State Department, February 6, 1968, LBJL, NSC Histories, Pueblo Crisis, 1968, box 34-5, volume 16, telegrams from Seoul, tabs 1-5; "propaganda tune" in New York Times, February 8, 1968, p. 15.)

Mobilizing for War

The situation inside the North was equally as tense. In 1966, rations started to be stockpiled and the training period for militias was extended, in preparation for the impending US attack that North Korean officials regularly predicted. Factories were relocated, street patrols were intensified, and the resettlement of families outside of the capital began in 1967. By the end of that year, North Korean citizens were not permitted to go more than 2 kilometers from their homes without official permission. Pro-government and anti-American rallies were organized to unify the people against the external threat. Allegations of impending American attacks were particularly common throughout 1968. In February, Pyongyang was placed on high alert to prepare for an attack, students were taken out of schools, and many residents were ordered to relocate to the countryside. All Koreans older than four were required to carry backpacks of necessities in case of emergency evacuation, and the government started assigning people to the mountain regions to dig protective bunkers. Air raid alerts were run regularly; air raid shelters were constructed; leading officials and scientists were evacuated from the cities; and romantic stories, operas, and love songs were banned, in order to ensure that the people were focused on the threat from the West.

Many on the Communist side expected war. "If the DPRK does not accede to U.S. demands to return the ship and crew," the Polish Ambassador to North Korea lamented, "we might probably witness an armed conflict here." ("Note on a Conversation with the Polish Ambassador, Comrade Naperei, on 26 January 1968, in the Polish Embassy," GDR Embassy to DPRK, 27 January 1968, in Lerner, “Mostly Propaganda by Nature.”) Chinese officials reported that the North Korean people were rallying for war, confident that the USSR and China would back them with nuclear weapons if needed. ("Excerpt from a Personal Letter of the Acting Ambassador of the GDR in Pyongyang, Comrade Jarck," attachment to a letter from GDR Foreign Minister Hegen to GDR officials, February 23, 1968, in Lerner, “Mostly Propaganda by Nature.”) Moscow desperately tried to keep Kim under control. The Soviet government, noted a Hungarian official, believes that, "the further prolongation of the crisis would be seriously dangerous…[and] strives to induce the DPRK to find a right time for handing over of the Pueblo and its crew…so as to put an end to the crisis." ("Report, Embassy of Hungary in the Soviet Union to the Hungarian Foreign Ministry, 30 January 1968," MOL, XIX-J-1-j Korea, 1968, in Lerner, “Mostly Propaganda by Nature.”) In mid-February, the Soviet Ambassador to the DPRK quietly informed Kim that "we need a peaceful resolution and a reasonable solution." ("Note on a Conversation with the USSR Ambassador, Comrade Suradikov, on 16 February 1968 between 16:15 and 17:30 hours," GDR Embassy to DPRK, Pyongyang, 20 February 1968, in Lerner, “Mostly Propaganda by Nature.”) Soviet frustration with their ally sometimes even exploded into the public arena, notably at the April 1968 Central Committee of the Soviet Communist Party Plenum, Party General Secretary Leonid Brezhnev blasted North Korea in a lengthy speech. North Korean officials, he reported, "spoke to the intentions to bind the Soviet Union somehow, using the existence of the treaty between the USSR and the DPRK to involve us in supporting such plans of the Korean friends, about which we knew nothing." ("Excerpt from Leonid Ilyich Brezhnev's speech at the April (1968) CC CPSU Plenum," On the current problems of the international situation and on the struggle of the CPSU for the unity of the international communist movement, 9 April 1968, Russian Government Archives of Contemporary History, in Lerner, “Mostly Propaganda by Nature.”)

Still, the DPRK refused to yield, demanding the United States apologize and take other actions to ensure that the "national dignity of the DPRK was not insulted." ("Information about the Situation in Korea," p. 15.) The North massed its defense forces along its harbors and the DMZ, and kept a number of jets constantly in the skies. Nor were their actions strictly defensive. Kim, lamented a Polish member of the Neutral Nations Supervisory Commission shortly after the Blue House and Pueblo attacks, was still launching "continuous attempts" to infiltrate South Korea with commandos. ("Note on a conversation with the Polish Ambassador, Comrade Naperei, on 26 January 1968, in the Polish Embassy," p.1, in Lerner, “Mostly Propaganda by Nature,” NKIDP Working Paper #3.) In April 1968, an ambush of a United Nations Command (UNC) truck along the DMZ left four UNC soldiers dead. A few months later, the Polish Ambassador to the DPRK reported that armed clashes over the preceding six weeks had resulted in an estimated 30 deaths along the southern side of the DMZ. ("Note on the Farewell Visit of the Polish Ambassador to the DPRK, Comrade Naperei, with Comrade Jarck on 26 July 1968, between 11:00 and 12:30 hours," GDR Embassy to DPRK, July 29, 1968, in Lerner, “Mostly Propaganda by Nature.”) In October, the North landed approximately 120 soldiers at different locations along the east coast of South Korea, between the towns of Ulchin and Samchok, sparking a series of fights that left 63 Southerners and many more Northerners dead. The violence had reached levels not seen since the end of Korean War in 1953, and there seemed no end in sight. "The recurrence of similar events can be expected," predicted the East German Ambassador to the DPRK. "Thus the tensions, which are also created by other factors, will certainly not diminish but rather will increase." ("Excerpt from a Personal Letter of the Acting Ambassador of the GDR in Pyongyang, Comrade Jarck," p. 1, in Lerner, “Mostly Propaganda by Nature.”)

De-escalating the Crisis

De-escalating the Crisis

This dire prediction, however, soon proved erroneous. North Korea began to reverse course in 1969, and tensions returned to the level of the years that had preceded the Second Korean War. Military incidents still occurred occasionally, most notably the DPRK shoot-down of an American EC-121 reconnaissance plane that had been conducting aerial intelligence collection operations about 70 miles southeast of Chongjin, killing all 31 Americans on board. Still, Northern bellicosity was clearly on the wane. The number of firefights along the DMZ fell from 236 in 1968 to 39 in 1969. ( Bolger, Scenes from an Unfinished War.)The Pueblo men came home, and within a few years the Nixon administration began publicly discussing the possibility of removing most American troops from South Korea. Still, the period of the Second Korean War stands as one of the most dangerous times on the Korean peninsula since 1953.

Explaining the DPRK's Aggression

Explaining the DPRK’s Aggression
There remains much scholarly debate over the causes of the North Korean aggression. Most interpretations for Pyongyang's belligerency during the Second Korean War can be lumped into one of six general explanatory categories. The first, which has been largely discredited, suggests that the North Korean attacks were actually defensive, driven by increased South Korean and American provocation. (See, for example, Frank Baldwin, ed., Without Parallel: The American-Korean Relationship since 1945 (Pantheon, 1974), p. 33, and Park, Tae-Gyun, "Beyond the Myth: Reassessing the Security Crisis on the Korean Peninsula during the mid-1960s," Pacific Affairs, Volume 82, spring 2009, p. 93-110.) As more evidence from the archives of the DPRK's allies has emerged, however, it has become clear that North Korea was the aggressor and this interpretation in largely unsupportable. While there is no doubt that South Korean officials did try to use the growing crisis to manipulate their American benefactors, the overwhelming preponderance of evidence suggests that the North provoked the vast majority of the military confrontations. "The incidents in the demilitarized zone and to the south of it," concluded a lengthy report from the Czechoslovakian government in 1968, "are intentionally and purposefully provoked mostly by the DPRK." ( "Information about the Situation in Korea," February 5, 1968, State Central Archive, Prague, Central Committee of CPCZ Archive, File #3750, Fund 02/1, Vol 68, Ar. J. 61, p. 13, in Mitchell Lerner, “Mostly Propaganda by Nature,” NKIDP Working Paper #3.)

The Vietnam War

The Vietnam War
Other interpretations, however, exist. One argument puts the Vietnam War at the center of the equation. Noting the similarities of timing between the American escalation in Vietnam and the DPRK actions, some have speculated that the two were connected, suggesting that Kim was trying to help his Vietnamese allies by forcing the American military to divide its resources between the two fronts; that he had been inspired by the success of the guerilla tactics of the North Vietnamese, and believed that similar tactics might work in Korea; or that he believed that America's commitment in Southeast Asia would prevent the U.S. from responding forcefully to his provocations against the South. (See, for example Robert Scalapino and Chong-Sik Lee, Communism in Korea (University of California Press, 1972), p. 594-6; Vandon Jenerette, "The Forgotten DMZ," Military Review, Volume 68, number 5, May 1988, p. 32-43; Donald Zagoria and Young Kun Kim, "North Korea and the Major Powers," in Asian Survey, Volume 15, December 1975, p. 1018; Narushige Michishita, "Calculated Adventurism," The Korean Journal of Defense Analysis, Volume 16. Number 2, Fall, 2004, p. 187; and Daniel Bolger, Scenes from an Unfinished War, chapter 1, on-line at: (last accessed December 14, 2009).)

Coldwar Geopolitics

A third internationally-centered explanation is even broader, as it connects the DPRK escalation to changing circumstances within superpower Cold War relations. Proponents of this school suggest that Kim felt that the growing US-USSR rapprochement, by removing the threat of Soviet reprisal, had encouraged the US to increase its attacks against the smaller communist nations; North Korea, in this argument, had little to lose by increasing its activities against the South since the U.S. likely felt safe planning increased actions against them regardless. (Soon Sung Cho, "North and South Korea," in Asian Survey, Volume 9, January 1969, p. 35-6.)

The declining DPRK-China relationship is also part of this view, as some suggest that Kim felt abandoned by the Chinese, because of their focus on the Cultural Revolution, and that the Revolution had opened the door to Kim to emerge as the dominant Asian communist leader, but only if he could first demonstrate to other Communist states his commitment to fighting Western imperialism. (Bernd Schaefer, "North Korean 'Adventurism' and China's Long Shadow, 1966-1972”; Bradley Martin, Under the Loving Care of the Fatherly Leader: North Korea and the Kim Dynasty (Thomas Dunne, 2004), p. 121-24. ) Regardless of the specific interpretation, however, this school is generally united by the belief that changing external circumstances, largely rooted in Beijing, Moscow, and Washington, were central in driving the DPRK policies.

Inter-Korean Competition

Other interpretive schools find the fundamental cause to be much closer to home by placing South Korean developments at the forefront of the escalation. In this interpretation, Kim recognized the growing economic might and political stability in South Korea, rooted in the consolidation of power of the Park Chung Hee government, the massive economic and material support coming from the United States, the 1965 normalization of ROK-Japan relations, and the elimination of most of the pro-Kim underground groups in the South.

Fearful of falling behind in this critical competition, Kim thought it necessary to act to balance the scales, and hoped to weaken the Park government through these guerilla attacks before his opportunity was lost. (See, for example, Charles Armstrong, Necessary Enemies," US-Korea Institute Working Paper Series, WP 08-03, September 2008, p. 6; Bolger, Scenes from an Unfinished War; Balazs Szalontai, Maneuvering Between the Battling Whales: North Korea’s Involvement in the Second Indochina War, 1964-1975, unpublished paper in author's possession; Yong Soon Yim, "The Dynamics of North Korean Military Doctrine," in Kwak, The Two Korea in World Politics, pp. 124-26)

Shifting Domestic Political Structure in the DPRK

A final framework shifts the focus from the international to changing internal DPRK life. Two specific interpretations dominate this school. The first focuses on the emergence of a more hard-line faction in DPRK politics. Kim, in this argument, began in the late 1960s to rely more closely on a group of conservative, largely military, leaders who supported greater emphasis on military and defense spending, a focus on heavy industrial growth at the expense of consumer products, and a reduction of Chinese influence within their government. The growing influence of these more aggressive figures thus birthed the more strident military maneuvers against the South, designed both to reunify the country and justify the pro-heavy industry and military development positions of these men, according to this interpretation. (Dae-Sook Suh, Kim Il Sung (Columbia, 1988), especially p. 227-248; Mobley, pp. 103-04.) Another explanation that focuses on the domestic argues that the internal tumult within the DPRK on both the political and economic levels was at the heart of the matter. This school suggests that Kim created this military crisis with the West in order to distract the public from their economic hardships, to have a convenient scapegoat for his economic failures, to silence his limited domestic opposition, and especially to re-assert himself as the great leader demanded by the critical Juche ideology that defined the nation. ( Mitchell Lerner, "Mostly Propaganda in Nature:" Kim Il Sung, the Juche Ideology, and the Second Korean War,” NKIDP Working Paper #3; Dae-Ho Byun, North Korea’s Foreign Policy (Seoul, 1991))


Regardless of the causes of the Second Korean War, though, the consequences would live on well after its resolution. The human cost would be significant; one leading military source estimates almost 400 ROK or American military deaths from this period (communist sources are unreliable on the numbers killed on their side). (Bolger, p. 112.) The tension between the divided Koreas was reinforced, with the hostility from both sides renewed and increased. Americans, although quickly turning their focus back to Vietnam, were reminded that other potential hotspots in Asia existed. Despite some personal tensions between leaders, the political connections between the US and the ROK were generally strengthened, especially by the dramatic increase of economic and military aid the US provided. South Korean President Park also used the crisis to help strengthen his political regime and consolidate his power, often at the expense of civil liberties. The North’s provocations, on the other hand, served largely to drive a wedge between the Kim regime and its superpower allies, especially the Soviet Union, although it did win some support from smaller communist states that admired Kim’s aggressiveness. In the end, though, while the Second Korean War may have altered the strategic situation on many specific levels, it largely just solidified the status quo that would characterize the second half of the twentieth century on the Korean peninsula.

Suggested readings:

Armstrong, Charles. Tyranny of the Weak. Ithaca: Cornell University Press, 2013.

Bolger, Frank. Scenes from an Unfinished War. Ft. Leavenworth: Combat Studies Institute, 1991.

Martin, Bradley. Under the Loving Care of the Fatherly Leader: North Korea and the Kim Dynasty. New York: St. Martin’s Griffin, 2006.

Lerner, Mitchell. "Mostly Propaganda in Nature:" Kim Il Sung, the Juche Ideology, and the Second Korean War.” NKIDP Working Paper #3, 2010.

Lerner, Mitchell. The Pueblo Incident. Lawrence: University Press of Kansas, 2000.

Radchenko, Sergey. “The Soviet Union and the North Korean Seizure of the USS Pueblo: Evidence from Russian Archives.” CWIHP Working Paper #47.

Sarantakes, Nicholas. “The Quiet War: Combat Operations Along the Korean Demilitarized Zone, 1966-69.” Journal of Military History, April 2000.

Schaefer, Bernd. “North Korean Adventurism and China’s Long Shadow, 1966-72.” CWIHP Working Paper No. 44.