Anti-deterrence: the 1949 case study

Withdrawal of US forces from Korea was followed by an immediate invasion

Could we have done something to deter Russia’s invasion of Ukraine? History offers many lessons, and one from the “forgotten war” stands out — not just in how peace has been kept since hostilities ended in 1953, but more importantly in the signals sent in the year preceding the attack. The Korean War is a case study of how withdrawal of US combat forces acts as a green light to foreign invasion.

A review of the dozen books that I own covering the Korean War, President Truman, and the Cold War in general, plus a focused scan of books I found at the library have not covered the buildup to war in enough detail to illuminate the anti-deterrence thesis I posited above. So I found myself digging into the NY Times archives, which is what I want to share here. The articles are not fully digitized, so I can only snip and paste. Fascinating stuff.

The backstory involves Russia and the United States agreeing to occupy the Korean peninsula after Japan’s surrender in August of 1945. US forces arrived almost immediately after WW2 ended, occupying the southern half of Korea, while Soviets arrived to occupy the northern half. Their deal was to reunify Korea, but the Soviets weren’t honest partners and instead backed Kim Il Sung as their communist autocrat in Pyongyang. The Americans soon agreed to a mutual withdrawal of Soviet and US forces, leaving Korea to the Koreans, but secretly the communists were plotting to invade.

Well, the secret commie plot to invade anywhere and everywhere is a myth. In fact, Josef Stalin was ambivalent. Archival research has now revealed that Stalin authorized Kim Il Sung’s invasion in early 1950 only after numerous signals of passivity from the US government — including speeches by SecState Acheson, neglect by General MacArthur, votes by Congress, and the total removal of all US troops from the peninsula.

It all reminds me very much of the signals of American passivity in 2021 concerning Ukraine.

Keep in mind, North Korea was much richer and more industrialized at the time, and the NK army was battle-hardened after years of fighting alongside Mao in revolutionary China. Troops in the Republic of Korea (ROK) were inexperienced, untrained, and barely equipped.

Basic Timeline :
(1) US troops occupy/defend from 1945 until …
(2) US troops withdraw in June, 1949.
(3) NK invades on June 25, 1950.
(4) US combat troops return around July 1, 1950.

I don’t know why the Truman administration agreed to withdraw US forces, and that’s not my objective right now. I just want to understand the timeline. The story as I understood it was that US combat troops were withdrawn in June 1949, followed exactly one year later by the invasion of North Korea’s army on June 25, 1950. Dates are important here, but Max Hastings book (which I had on my college dorm bookshelf) opens with an account of a poorly supplied US Army infantry unit fighting a column of North Korean tanks on July 5, 1950.

Yet the more I dig, the more the lines blur. For starters, the NK army was doing large scale attacks across the 38th parallel (border) almost immediately after US combat forces left in 1949. Furthermore, a contingent of American forces remained on the peninsula in an advisory role, though for how long is unclear. Here are the firsthand accounts of note:

June 29, 1949. Last US Combat Troops Withdraw. (NYT article)

What got my attention was an article (all articles mentioned here are from the NY Times) on June 29, 1949 reporting that all combat forces departed that day with the exception of a 500-person advisory force remained.

What? Five hundred is a sizeable force and seems a formidable tripwire. What I don’t know are the answers to these questions: How long was this advisory force under the command of BGEN William L. Roberts in place? Everything I have found indicates that the 500-strong American group remained in Korea. Maybe it was pulled? But if not, where was General Roberts and how did he react when he learned of the invasion? Did these US advisory forces engage in any fighting? The books I have in hand are silent on this.

August 5, 1949. Peril in Korea (editorial)

“The invasion of South Korea by a force of 4,000 to 6,000 men cannot be casually dismissed as a mere border foray on the Thirty-eighth Parallel. Manifestly the Communists from the north are both probing the south's defenses and undertaking to strengthen their own positions.”

This editorial is emphatic that the United States has an obligation to support the South Koreans as a matter of “honor and self-respect” if nothing else.

January 19, 1950. 2 Votes Block Korea Aid Bill.

House Test a Blow to Truman

Republicans and Southern Democrats Join, Apparently Piqued by Stand on China— Money Is Held Going Down 'Ratholes'

WASHINGTON, Jan. 19—In a major blow to Administration policy in the Far East, a coalition of Republicans and southern Democrats in the House, hitherto in prevailing combination only on domestic issues, defeated today a bill to provide $60,000,000 in economic aid for the Republic of Korea.

It’s interesting to see how partisan lines were blurrier in those days, given that most Democrats supported Truman though 61 voted against, whereas 1 out of every 8 Republican congressmen supported the president. Regardless, the vote was a powerful signal. Congress made clear that it wouldn’t supply combat forces or military aid, despite President Truman’s support. Thus the regime in Seoul did not have fighter aircraft, nor tanks, nor even anti-tank weapons to resist the Russian-made tanks that invaded across the 38th parallel in 1950.

How strongly history rhymes.

FURTHER READING: Answers to the questions posed here can surely be found in US Army studies. One came to my attention soon after publishing, a 2009 monograph by John Tabb (Major, US Army) titled The Korean Military Advisory Group (KMAG): A Model for Success? In addition to the extraordinary bibliographic review, Tabb details how most KMAG members were being evacuated, but a few remained with their ROK units. These brave few essentially led ROKA units in combat and maintained the only link to MacArthur’s HQ in Japan — the pivotal communication chain that convinced those units to resist the invaders in the faith that American combat forces would reinforce.