KIMS Periscope

KIMS Periscope No. 347

The U.S. Navy’s Experience in Coalition Warfare in the Korean War

U.S. Air Force’s Air War College
Prof. Corbin Williamson
The Korean War (1950-1953) brought together forces from nine navies under an American naval command structure to defend South Korea. Many of the personnel who served in these navies had experience with coalition warfare from World War II which aided personal interoperability. The absence of serious naval opposition in Korea gave the Korean War its own unique character, distinct from World War II. The overall objectives of U.N. naval forces were to support the U.N. ground forces fighting to secure South Korea on the Korean peninsula. Units from these navies typically operated off either the Korean east coast or west coast to perform a range of missions including flying air strikes, launching amphibious operations, bombarding targets ashore, minesweeping, blockading, and escorting supply ships. 
While the international political context of 2024 is different from 1950, the U.S. Navy’s experiences in coalition warfare during the Korean War highlight enduring factors in coalition operations such as the value of exercises and the challenges of communications and equipment differences. Examining the pressures, opportunities, and potential pitfalls of multinational naval operations in the Korean War can help officials today ask better questions about international naval cooperation.
When the Korean War broke out in June 1950, British and American commanders formed a British-American carrier force which began attacking targets in North Korea within eight days. This rapid response reflected both the inherent flexibility of naval forces and the benefits of Anglo-American naval exercises held earlier that year. For two weeks in late February and early March 1950, British and American warships exercised together in the South China Sea. Over the course of these exercises, the two sides operated as opposing forces before joining up for a series of combined training events.These combined events involved practicing combined air defense, offensive carrier strikes on land targets, underway replenishment from each other’s ships, and cross-decking (landing and launching aircraft from the other side’s aircraft carrier). These practice events would prove useful when the Korean War broke out as naval forces were tasked with similar missions. For the duration of the spring 1950 exercises the British adopted U.S. Navy tactical and signal books for maneuvering and communication purposes. 
At a combined post-exercise analysis and critique in the Philippines, officers from both navies concluded that there were no serious obstacles to ships from the two navies operating together.
Three months in June 1950 later some of the ships and crews that participated in the spring exercises, such as the British carrier Triumph and the American heavy cruiser Toledo, were sent to Korean waters in response to the North Korean invasion of South Korea. The British ships sent to Korea immediately adopted American naval books as they joined up with American forces, some of whom had recently operated with the British. 
British Rear Admiral William Andrewes, who had participated in the spring 1950 exercises, commented in July 1950 that operating with the U.S. Navy “all seemed so familiar” because of these exercises earlier that year. The skills and experience gained in these exercises helped British and American naval forces come together rapidly after the North Korean invasion. However, exercises did not lead to frictionless coalition naval operations.
Communications challenges proved to be an enduring theme of multinational naval operations in the Korean War. 
The outbreak of war resulted in a torrent of radio traffic transmitted to American and allied ships with higher classification and priority than peacetime traffic. Operational messages with time-sensitive orders competed with messages about reinforcements and weather updates for scarce radio space. U.S. Army and U.S. Air Force messages were frequently sent to coalition naval units to improve coordination between the services. However, these non-naval messages were typically longer than comparable naval traffic which was more concise by design. To handle this explosive growth in radio traffic the communications section of the American naval headquarters in Tokyo increased in size from 57 personnel in June 1950 to 415 personnel by the end of November 1950. Unfortunately, British ships did not carry as many communications personnel or radio circuits as comparable U.S. Navy warships. As a result, Royal Navy ships at times had difficulty keeping up with the scale of radio traffic pouring in from American commands. 
The growing scale of radio traffic was not helped by problems with cryptography. The American naval command for the Korean War provided non-American ships with access to certain ciphers to allow for secure radio communications while retaining other ciphers for U.S.-only use. However, sometimes messages were sent to non-American ships in these U.S.-only ciphers which allied ships could not break. The solution was for nearby American ships or stations to retransmit such messages in multinational ciphers or to request that the originating unit retransmit the message. Either approach typically resolved the issue but at the price of producing even more radio messages and increasing the already high scale of communications.
In an effort to improve the efficiency of coalition naval operations in Korea, in 1951 and 1952 standard North Atlantic Treaty Organization (NATO) tactical and communication books were brought into use in Korea. Overall, these standard books developed for NATO did make multinational communications and tactical maneuvering easier. However, the introduction of these books at times made naval operations more difficult since different navies adopted these books at different speeds. In particular, British and Canadian ships began using these books sooner than their American counterparts, which led to confusion at times. Furthermore, the degree to which these books could be shared with other nations was not always well understood. British naval reports from the Korean War note that on occasion U.S. Navy officers initially refused to show NATO publications to British personnel until the Royal Navy’s role in creating these documents was clarified. The need for secure communications that could handle traffic between units from different navies without unnecessary administrative burdens proved to be a difficult requirement to fulfill throughout the war.
Equipment Capabilities
Communicating between ships and aircraft of different navies could also be hindered by differences in communication equipment, specifically whether the unit had both Very High Frequency (VHF) radio and Ultra High Frequency (UHF) radio or just VHF. Such differences in equipment between coalition navies during the Korean War at times caused problems while in other instances proved useful. After World War II the U.S. Navy began introducing UHF radio throughout the fleet and many American ships and planes were equipped with UHF during the Korean War. The Royal Canadian Navy followed suit, introducing UHF radio to retain the ability to communicate with American ships. However, Britain’s Royal Navy did not introduce UHF fleet-wide until after the Korean War due to concerns about the cost of the change. As a result, there were instances during the war when American units would attempt to communicate with British units via UHF radio and the message could not be received. The solution adopted was to use VHF for communication in multinational formations.
Differences in equipment also shaped the way units from different nations were employed during the Korean War. At the start of the war in early July 1950, the American carrier Valley Forge and the British carrier Triumph operated together, attacking targets in North Korea. The first day of strikes highlighted the fact that Triumph’s aircraft did not have as long range as their American counterparts. For the second day and subsequent days of combined operations, Triumph’s aircraft flew defensive patrols around the carrier force while Valley Forge’s aircraft conducted offensive strikes. The British report on these operations described this division of labor as “galling but unquestionably correct” given the longer range of American carrier aircraft, especially the AD Skyraider.
Such differences in equipment were not always in the U.S. Navy’s favor. 
Canadian destroyers in Korea were equipped with high-definition navigation radar which made these ships better able to detect low-lying obstacles, small boats, and rubber rafts than other U.N. warships. This Sperry navigation radar made Canadian destroyers ideal for littoral operations, especially in the shallow waters off the Korean west coast. The Canadian destroyer Athabaskan’s navigation radar proved valuable in early December 1950 soon after China’s intervention in the war. That month a Canadian-Australian-American destroyer force including Athabaskan sailed 35 kilometers up a narrow channel at night to reach Chinnamp’o where U.N. forces were evacuating due to the advances of Chinese forces. Athabaskan’s navigation radar aided this difficult navigational passage. Differences in equipment helped and at times hindered coalition naval operations.
The U.S. Navy’s experience with coalition warfare during the Korean War suggests factors and questions that officials, officers, and planners should consider when establishing policy and managing navy to navy relationships. First, regular exercises provide regular opportunities for units to practice multinational operations. The ability for naval forces to work together effectively on short notice is a perishable skill that requires practice like the recent exercises in mid-January between American, South Korean, and Japanese naval units in the East China Sea.  
The constant turnover of naval personnel in operational assignments underscores the need for coalition naval forces to regularly practice communicating, sailing, and flying together to establish and maintain interoperability.
Second, the challenges of multinational communications experienced during the Korean War have not ended. Finding ciphers, networks, and electronic platforms that can be used to securely and rapidly share information between navies in a multinational task force remains difficult. For example, a cipher or network authorized for American-Australian use may not be releasable to Japan or South Korea and vice versa. Furthermore, the pursuit of ever more sophisticated and capable communications equipment by large navies forces smaller navies to make hard choices between incurring the high financial cost of expensive, compatible communications equipment or reducing communications interoperability. The U.S. Navy’s transition from VHF to UHF during the Korean War represented a similar dilemma.
Third, differences in operational capabilities offer opportunities for multinational naval forces to be more capable than a single navy operating by itself while also presenting challenges to be managed. The high-definition navigation radar of Canadian destroyers in the Korean War gave U.N. naval forces a littoral operating capability that American destroyers lacked. Today, the variable depth sonars in the newest South Korean and Japanese destroyers and their diesel submarines provide capabilities that the U.S. Navy does not have. As officials consider how to spend finite budgets, relying on the capabilities of partners and allies can free up resources for other priorities.
A recurring theme in U.S. Navy reports from the Korean War is the sense that the war’s multinational naval coalition was a sign of things to come. The captain of the escort carrier Sicily wrote in March 1952 after operating with the British carrier Glory and Canadian destroyers:
It must be commented that the international character of the forces which comprise CTE [Commander Task Element] 95.11 were no obstacles to smooth operation. The excellent seamanship and efficiency of the various screen commanders was particularly notable. 
Combined operations of this kind are felt to be invaluable in building good will and a sound foundation for future United Nations cooperation.  
Such reports assumed that the Korean War’s naval experience had continuing relevance for future multinational naval operations. Examining the war’s operations can help officials today evaluate the present with a historical mindset, looking for similarities and differences between the present and the past.

Bowers, I. (Ed.). (2024). Coalition Navies during the Korean War: Understanding Combined Naval Operations (1st ed.). Routledge.

  • The opinions expressed in this article are the author’s own and do not reflect the view of KIMS. 

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