Failure to Communicate: U.S. Intelligence Structure and the Korean War

The seventeen different civilian and military intelligence organizations of the United States vary in coverage (collection targets and methods) and depth (from strategic, to operational, to tactical objectives). A variety of organizations working towards different purposes ensure that the intelligence community provides national decision-makers the best picture possible about situations around the world.

Intelligence at all levels is an art form. Sources, corroborating or contradicting information, unknowns, and delays in time all result in varied levels of analytical confidence. Information coming from different means, methods, and areas requires a functioning structure to ensure senior national leaders have the best information to make the decisions. While strategic intelligence drives operations and national goals, military decision-makers—especially in combat zones—rely on tactical intelligence to help win battles. For the Department of the Navy, “tactical intelligence support is the primary focus of naval intelligence.”[1] Marine Corps intelligence also focuses almost exclusively on the tactical level to support Marine Expeditionary Force (MEF) maneuvers since tactical intelligence is, “the level of intelligence Marines need, generate, and use most often.”[2] When strategic missteps occur, tactical intelligence can provide a needed capability to keep front-line forces winning, creating breathing room for new strategic plans. A functioning intelligence structure encompassing all levels of intelligence is needed to enact this goal.

Strategic intelligence analysis and the national intelligence structure failed during the Korean War on two well-known occasions: anticipating the initial North Korean invasion and ignoring the signs of large-scale Chinese intervention.[3] Inadequate manning and skill sets, erroneous target prioritization, and a failure to integrate tactical collection into strategic analysis all played a role in these missteps. Perhaps the most significant intelligence failure was the inability to separate personal opinions and the desire to please superiors when presenting intelligence:

The Yalu disaster was completely predictable. The intelligence failure was the result of a policy maker’s determination that intelligence support his preconceived views, not challenge them. It is a timeless lesson.[4]

Policy-makers in Washington and military planners throughout the Pacific continuously prepare for situations on the Korean Peninsula. Four mistakes from the Korean War showcase why tactical and strategic intelligence must coordinate and integrate to ensure battlefield success. As we contemplate the possibility of renewed open hostilities in Korea, the services must learn from prior experience. Success on the battlefield is a prerequisite for theater victory in the type of conventional conflict most likely to emerge in Korea.

Strategic Intelligence Failures

The Korean War had three distinct phases. The first phase began with the North Korean invasion across the 38th parallel in June 1950. North Korean armor divisions and infantry funneled south into Seoul, driving back both U.S. and South Korean soldiers en route to the southern tip of the peninsula. U.S. and Republic of Korea (ROK) forces established a defense around the port of Pusan—the Pusan Perimeter—while rushing reinforcements into the line and planning for a counterattack at Inchon. In September 1950, the amphibious landing at Inchon cut off North Korean lines and initiated the second phase of the war. U.S., ROK, and U.N. forces drove a demoralized and unsupplied North Korean army nearly back to the Chinese border. MacArthur’s decision to invade North Korea led to the third phase of the war—the Chinese decision to commit forces into the conflict. The costs of this misstep resulted in Truman’s decision to relieve General MacArthur and the U.N. retreat back to the 38th parallel. The war ultimately dissolved into a stalemate with battles back and forth across the border for two years until the armistice was declared in 1953.

Mistake 1. Post-WWII Manning and Capability Reductions

Each of the military services sustained severe manning reductions after the conclusion of WWII. Military intelligence services were no different. For example, the US 7th Fleet had only one intelligence officer in the Far East Command and massive manpower increases were required to fill the required staff positions.[5] Many American cryptologic personnel left or were forced out of the service. The reductions in personnel and funding led to increased competition between the Army, Navy, and Air Force cryptologic agencies.[6] In order to appease political superiors, the agencies voluntarily joined the Armed Forces Security Agency (AFSA), an umbrella Signals Intelligence (SIGINT) organization. However, the half-hearted merger resulted in an agency with no Korean linguists, Korean language typewriters, or Korean-English dictionaries.[7] These inefficiencies resulted in a near complete lack of SIGINT support until three months after the North Korean invasion. In fact, the first actual U.S. SIGINT-dedicated unit did not arrive in Korea until December 1950, almost six months after the war began.[8]

...front-line commanders of the initial forces in Korea arrived in country with little understanding or insight into the peasant Korean army pushing them back to the ocean.

The entire intelligence command structure in Asia was severely degraded at the outbreak of the war. Major General Willoughby, General MacArthur’s Far East Command senior intelligence officer, had only minimal personnel available. On paper, he managed two staffs out of Tokyo for the Far East Command and the Supreme Commander Allied Powers. In reality, from 1945 to 1950 the staff was reduced from 3,872 to 898 for analysis, operations, and administration.[9] These inadequate personnel numbers, insufficient regional specialists, and failure to work together laid the groundwork for a national structure incapable of providing timely and accurate intelligence to decision-makers.

Mistake 2. Over-Concentration on Strategic Requirements

Tactical-level intelligence capabilities were almost non-existent on the Korean Peninsula at the outbreak of the war. The Cold War and nuclear deterrence policy shifted the intelligence community focus to strategic intelligence collection on the Soviet Union, and, to a minimal extent, Chinese communism.[10] The few analysts working in Asia concentrated on strategic Soviet issues and proved insufficient to fill the needs of maneuver commanders on the battlefield.

The prioritization of targets was reflected by the published intelligence requirements. The Recurrent Intelligence Requirements List organized the collection topics for intelligence assets from ‘A’ items to ‘C’ items. ‘A’ items were most important, then ‘B’ items, and finally ‘C’ items. The ‘A’ list consisted of 20 requirements, one of which involved North Korea: “Soviet activities in North Korea”. Of the ‘B’ list’s 58 requirements, only two involved North Korea: “North Korean-Chinese Communist relations” and “North Korean-South Korean relations, including actions of armed units in border areas.”[11] The result of this prioritization was that front-line commanders of the initial forces in Korea arrived in country with little understanding or insight into the peasant Korean army pushing them back to the ocean.[12]

Another example of over-reliance on strategic targets was the use of communications-intelligence units. Available collection units were geographically spread throughout the Pacific theater but remained focused on the Soviets. The 111th Signal Service Company was in Korea up until July 1948 collecting on Soviets located directly across the 38th Parallel. When the Soviets left, so did the 111th, reducing U.S. communications-intelligence coverage on North Korean military and diplomatic radio traffic.[13]

...the South Korean army was ill prepared for war, but the warnings were ignored in Washington...

Structural failure and strategic prioritization seriously hindered prisoner-of-war (POW) interrogations. A basic HUMINT function, interrogation of POWs is an ample source of intelligence in conflict. During the Korean War, in late 1950 as North Koreans surrendered en masse, the POW system “fell apart.”[14] POWs were misidentified, improperly registered, and could not be relocated for follow-on questioning.[15] Interrogations during the war took place largely at the strategic level with a focus on strategic requirements. However, many POWs had ample access to tactical information that was improperly or under-exploited.[16] Strategic interrogations lasted weeks and in some instances months, as interrogators focused on higher-level requirements at the expense of time-sensitive tactical intelligence. Reporting pipelines for transferring tactical reports and field interrogation notes from line units to rear area interrogators were often slow or non-existent.[17] On many occasions, POWs with valuable tactical intelligence were seized by units who did not report their existence to senior interrogators for extended periods of time.[18] 

Mistake 3. Perception Bias and Improper Analysis

  Marines under cover of large boulder engage enemy forces who were unsuccessful in trapping the Marines | Wikimedia Commons

Marines under cover of large boulder engage enemy forces who were unsuccessful in trapping the Marines | Wikimedia Commons

For years before the war, analysts and officials warned policymakers about the problems in Korea. However, while much of this analysis provided indicators and warnings that an invasion was possible, it disregarded the invasion due to the commonly held belief by decision makers that the Soviet Union controlled North Korea’s decisions. Accurate tactical intelligence masked by poor strategic analysis became the “preferred art form” for intelligence reporting from the peninsula.[19]

The Central Intelligence Agency (CIA) reported in a Weekly Summary in late 1948 that a North Korean attack was possible, citing new roads towards the border along with troop movements, but stated that Moscow made decisions for Pyongyang, a claim the CIA previously presented in 1947.[20] Almost 10 months before the war, CIA director Rear Admiral Roscoe Hillenkoetter testified that the South Korean army was incapable of stopping a North Korean invasion.[21] The CIA published analysis in June 1950 stating that North Korean forces were deploying along the 38th parallel. They repeated Rear Admiral Hillenkoetter’s warning that the South Korean army was ill prepared for war, but the warnings were ignored in Washington and in the Far East Command due to a disbelief in the aggression, independence, and capabilities of Asian militaries.[22]

Senior civilian leaders in Washington and senior military leaders in Asia refuted reporting which could have altered the war due to groupthink and preconceived opinions.

Shortly before the North’s attack, U.S. SIGINT identified at least six of the nine Chinese armies relocating to Manchuria in preparation for crossing the Yalu River, but U.S. decision makers downplayed the reports.[23] CIA reporting at the time also indicated that more than 200,000 Chinese soldiers were prepping along the North Korean border.[24] However, the widespread belief that the Soviet Union would not allow the North Korean or Chinese forces to attack took precedence to the mounting evidence on the ground.[25]

Senior civilian leaders in Washington and senior military leaders in Asia refuted reporting which could have altered the war due to groupthink and preconceived opinions. These two intelligence errors—the North Korean attack and Chinese intervention—are possibly two of the gravest mistakes in U.S. intelligence history. The North Korean invasion, which could have been prevented with posturing and deterrence, cost hundreds of thousands of lives and dragged a reluctant America back into a large-scale war in Asia. The second, which could have been avoided by heeding the warning signs from intelligence agencies, third-party diplomats, and the Chinese themselves, escalated the war and laid the groundwork for three decades of Chinese-American hostility that followed.

Mistake 4. Interagency Competition and Personalities

The individual opinions of the generals in Asia led to additional intelligence errors. Their beliefs influenced not only recommendations to civilian leadership but altered the structure and channels of intelligence between Asia and Washington. General MacArthur and his staff did not believe that any Asian country would risk fighting the United States for fear of certain defeat:

Washington’s strategic theme [of Soviet control] also played well in Tokyo, where General MacArthur and his staff refused to believe that any Asians would risk facing certain defeat by threatening American interests…This belief caused them to ignore warning of the DPRK military building and mobilization near the border…It was a strong and perhaps arrogantly held belief, which did not weaken even in the face of DPRK military successes against US troops in the summer of 1950.[26]

The warnings were blatant. Zhou En-Lai, the first Premier of the People’s Republic of China, issued a public declaration that China would intervene on 30 September—the day after President Truman authorized the war—stating, “The Chinese People…will not supinely tolerate seeing their neighbors being savagely invaded by the imperialists.”[27] The Chinese sent multiple warnings to the U.S. about an invasion of North Korea via the Indian Ambassador in China and the British Ambassador in Washington.[28] Both the British and Dutch ambassadors in Moscow told the U.S. that China would intervene if UN troops crossed the 38th parallel. Despite the warnings, the Joint Chiefs of Staff and Secretary of State encouraged MacArthur to push north.[29] The intelligence, generally, was accurate but ignored. Thrown into the frontlines of war in Korea, tactical commanders faced an uphill fight to hold the line.

On some occasions intelligence wasn’t just ignored, but altered or minimized by restructuring. Strong evidence exists showing that senior military leaders, including General Willoughby, were involved in these activities.[30] For instance, when CIA reporting indicated the large-scale movements of the Chinese army long the Manchurian border, Willoughby ordered the intelligence reports suspended and ordered the CIA to cease passing intelligence directly to Washington.[31] On another occasion in November, Willoughby minimized order of battle numbers by only counting prisoners as being from four different battalions instead of the four different armies which interrogation reports stated.[32]

The primary reports used by senior civilian leaders to make decisions in Korea were Daily Intelligence Summaries (DIS). General Willoughby supervised the construction of the DIS and created a narrow intelligence pipeline through which information would reach Washington. Ninety percent of the Pentagon’s intelligence flow came from such reports, and Willoughby prevented tactical and operational intelligence regarding the Chinese and American setbacks from making its way into the DIS.[33] American and UN policymakers based countless decisions on intelligence which did not properly depict the situation on the ground or the indications and warning of escalation.

Military leaders in the Pacific also mistrusted each other and the young civilian intelligence agencies.

Military leaders in the Pacific also mistrusted each other and the young civilian intelligence agencies. Willoughby and MacArthur refused to cooperate with the CIA and denied them access to Army reporting and facilities.[34] The Air Force and Army refused to combine human intelligence efforts in Korea, specifically with regards to interrogations. The Air Force created their own interrogation team that competed with the Army’s Korean Liaison Office (KLO) and CIA for intelligence, each meeting with limited success.[35] The Navy had no interrogators in Korea and interrogation reports from other services answered few naval intelligence requirements despite many of the POWs coming from port areas.[36] Tactical HUMINT operations lacked a structure for coordination and intelligence sharing which hindered operations and intelligence sharing.

Tactical Intelligence Holds the Line

While policy-makers in Washington analyzed less-than-accurate information from MacArthur’s intelligence services, accurate and timely tactical intelligence helped win battles in Korea that were necessary to provide time for strategic plans to develop. Despite their limited numbers and capabilities, especially at the beginning of the conflict, on-the-ground intelligence assets on the Korean Peninsula provided usable information to supported commanders.

  Repatriated POW Capt. Frederick Smith is greeted by his father on his arrival at Fort Mason, California, on board the USNS Marine Phoenix, September 14, 1953.

Repatriated POW Capt. Frederick Smith is greeted by his father on his arrival at Fort Mason, California, on board the USNS Marine Phoenix, September 14, 1953.

Peninsula-based SIGINT assets proved vital at the Pusan Perimeter and helped commanders relocate forces to best defend against North Korean attacks.[37] SIGINT identified the locations of enemy infantry battalions, ammunition deliveries, radio outages, and new aircraft runways and shelters. During lulls in the fighting, tactical SIGINT identified the locations of the next attacks through requests for river-crossing equipment.[38] This information allowed U.N. forces to defend the 140-mile line with significantly fewer troops and free up more men for the landing at Inchon. Tactical SIGINT’s value was proven time after time by identifying Chinese attack locations in such instances as the Battle of White Horse Mountain, Battle of Old Baldy, and Pork Chop Hill.[39] At White Horse Mountain:

Intercepted Chinese communications gave the Americans warning of the attack. ASA rushed an intercept unit to the spot, and it fed American commanders with hard intelligence as the battle progressed. The Chinese lost 10,000 troops out of the 23,000 they had committed.[40]

Tactical HUMINT was exploited throughout the war, especially during the preparation for Inchon. Operation Trudy Jackson, a joint CIA-Navy operation, prepared the environment for the invasion. One naval officer, two Korean operatives, and three others landed on Yonghung-do Island west of Inchon and trained guerilla fighters, launched raids, and gathered intelligence. At one point up to 150 guerillas conducted island-hopping operations around Inchon.[41] The intelligence gathered was vital to the landings and included the numbers of Chinese personnel crossing the Yalu River, tide times and levels, soil compositions, seawall heights and locations, current flows, and enemy locations.[42],[43]

Learning from Structural Intelligence Failure

The intelligence failures from Korea demonstrate the downstream effects from changes in national policies and an inefficient intelligence structure. When Washington became solely focused on Soviet nuclear weapons, the intelligence community adjusted in stride. When senior leaders re-organized and over-emphasized reporting which supported their biases, analysis and reporting fell in step. The result was not one, but two blindsides in Korea to begin the Cold War. Korea demonstrates three intelligence lessons for planners to consider.

First, an inability to properly integrate strategic and tactical intelligence leads to weak analysis and, thereby, poor decision-making. Second, multiple reporting outlets to senior leaders must exist to prevent stove piping. Decision-makers in Washington need varied and sometime contradicting analysis to ensure a single senior intelligence leader cannot alter decision-making by downplaying or overemphasizing different sources. Finally, a robust and responsive tactical intelligence capability is necessary to hold the line when higher analysis and leaders make mistakes. Accurate and timely tactical intelligence provides the space in which operational and strategic leaders can alter and execute plans. Ultimately, these four failures of U.S. intelligence led to an unfinished war with the next steps still being hypothesized today.

Christian H. Heller is an officer in the U.S. Marine Corps. He is a graduate of the U.S. Naval Academy, Oxford University, and was a Rhodes Scholar. The views expressed in this article are the author’s alone and do not represent those of the United States Marine Corps, the Department of Defense, or the United States Government.

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Header Image: Chinese POWs captured by U.S. forces, December 1950 | Wikimedia Commons


[1] Naval Doctrine Publication (NDP) 2, Naval Intelligence, 6.

[2] Marine Corps Doctrinal Publication (MCDP) 2, Intelligence, 52.

[3] Peter C. Unsinger, “Three Intelligence Blunders in Korea,” in International Journal of Intelligence and Counterintelligence, Volume 3, Issue 4, 1989, 549.

[4] Bruce Reidel, “Catastrophe on the Yalu: America’s Intelligence Failure in Korea,” The Brookings Institute, 13 September 2017,

[5] Wyman Packard, A Century of US Naval Intelligence, Department of the Navy, Washington, DC, 1996, 29.

[6] Tomas R. Johnson, “American Cryptology During the Korean War,” 30.

[7] Ibid, 31.

[8] Ibid.

[9] Charles M. Azotea, “Operational Intelligence Failures of the Korean War,” School of Advanced Military Studies, 15.

[10] Ibid, 6-12.

[11] Clay Blair, The Forgotten War (New York: Times Books, 1987), 171,

[12] See T. R. Fehrenbach, This Kind of War. Fehrenbach talks at length in his Korean War classic about both the lack of information or the misinformation provided to the first Army forces in Korea as the North Koreans forced them back to the Pusan Perimeter in 1950, much of which focused on the weakness and lack of capabilities in the peasant North Korean army.

[13] Azotea, 27.

[14] “Intelligence and Counterintelligence Problems During the Korea Conflict,” Military History Section of HQ, US Army, 31, (hereafter referred to as Intelligence and Counterintelligence)

[15] Ibid.

[16] Ibid, 7.

[17] Ibid, 34.

[18] Ibid, 5.

[19] Ibid, 16-17.

[20] P. K. Rose, “Two Strategic Intelligence Mistakes in Korea, 1950: Perceptions and Reality,” in Studies in Intelligence, No. 11.

[21] Packard, 29.

[22] Ibid.

[23] Johnson, 33.

[24] Alexander Ovedenko, “(Mis)interpreting Threats: A Case Study of the Korean War,” Security Studies, Vol 16, Issue 2.

[25] Douglas A. Borer, “Problems in the Intelligence-Policy Nexus: Rethinking Korea, Tet, and Afghanistan,” Intelligence and National Security, Vol 29, Iss. 6, 2014, 10.

[26] Rose.

[27] Yufan, Hao and Zhihai, Zhai, “China’s Decision to Enter the Korean War: History Revisited”, in The China Quarterly, No. 121, Pg 10

[28] Rose.

[29] Ibid.

[30] Borer, 8.

[31] Ibid, 12.

[32] Ibid, 14.

[33] Ibid, 10-13.

[34] Azotea, 18.

[35] Azotea, 17.

[36] Ibid, 20.

[37] Johnson, 32.

[38] Blair.

[39] Johnson, 35.

[40] Ibid.

[41] “Operation Trudy Jackson – Focus on Incheon Part 4,”

[42] “Inchon 1950: Operation Trudy Jackson,”

[43] Eugene Franklin Clark, The Secrets of Inchon: The Untold Story of the Most Daring Covert Mission of the Korean War (Putnam Adult, 2002)