I wonder this because it seems rather odd to me that Park Chung-hee, a collaborator and informant of the Japanese during their occupation would later be dictator of South Korea. How was it possible with all the continual tension over "comfort women" in Korea that a guy who snitched on his countrymen would be an approved dictator? Why didn't the U.S. Have any issues with this?
De-nazification and Japanese collaborators are two entirely different animals.
First, while the US felt more vengeful towards Japan due to Pearl Harbor, the bulk of the US war effort was sent to Europe first. Racial views of the Japanese (and Asians in general) tended to be more "paternalistic" (those poor Asians simply need American (WHITE) guidance to be good people) while the Germans were viewed as equals to the American and British. The Germans needed de-Nazification while the Japanese simply needed guidance.
But in regards to Korea, removal of Japanese collaborators was NOT an American issue. Korea was liberated from Japanese rule and the United States knew nothing about Korea. The division of Korea on the 38th parallel was made arbitrarily. When Dean Rusk, one of the officers who chose the 38th, was told that the Japanese and Russians had agreed to that line during the Treaty of Portsmouth said that, had he known, he would have chosen a different line.
In fact, so little was known that the United States left the Japanese administration in place when they took over! Shortly thereafter, the Japanese administration was dismantled, but the Japanese were kept around as advisors as the US didn't understand the political situation.
The Political Situation
It's critical to understand that the Japanese didn't just decide one day to annex Korea. They didn't walk right in and take over. Modern Korean-Japanese relations started in 1876, with the Japan-Korea Treaty of 1876/ Treaty of Ganghwa. This treaty forced Korea into an unequal deal with Japan, granting Japanese citizens extraterritoriality (freedom from prosecution for crimes committed in Korea) as well as many other one-sided rights. It also drove a wedge between the Koreans and Qing China by stating that Korea was a sovereign nation, equal to Japan. The Japanese completely severed the Korean-Chinese relationship in 1894-95. When the Tonghak rebellion began in Korea, the Joseon court called on the Qing to help put down the rebellion. The Qing did so, but didn't notify Japan as per an agreement between the two that they would notify each other whenever sending troops into Korea. The end of the first Sino-Japanese war resulted in Qing China being totally pushed out of Korea, Japanese troops stationed in Pusan, Jemulpo (Incheon)/Seoul, and Pyongyang, among other places, and a serious crisis in Korea. The Joseon Dynasty switched from a kingdom to an empire, and the Great Korean Empire came into existence. From 1894 until 1910, the Korean government was being torn between two sides - the pro Japanese side and the pro China/Russia/independent side(s). This brings us to 1905 and the Eulsa Treaty. Emperor Gojong refused to sign the treaty but five of his ministers did:
These five men have been labeled the Five Eulsa Traitors (을사 오적) and subsequently were targets of assassination attempts. Yi Ji-yong had his house burned down, and Gwon and Yi Wan-yong were both injured in attempts on their lives.
This information is critical to understanding the issue of collaboration. Many of the collaborators were of the upper-classes and they welcomed the Japanese in over a period of 34 years prior to outright annexation. They continued to work with the Japanese out of economic considerations during the colonial era. When the colonial era came crashing down, they were judged by their peers, not the common folks.
Your question
Were there purges of Japanese collaborators in post WWII Korea?
Yes, there were. However, the United States had nothing to do with these purges. Koreans who were part of the Japanese war machine were punished alongside the Japanese, however Koreans who were part of the colonial government from 1910-1945 were of no concern to the Americans. Also, and most importantly, the people who collaborated with the Japanese to begin with were the upper-classes. The five men above were all members of the yangban class, the wealthy elites. When the Republic of Korea was established in 1948, the government did go after collaborators. The Rhee administration submitted nearly 700 names to a special prosecutor which prosecuted around 200 cases of which only a few dozen convictions arose. Once the Korean War started the issue of the chinilpa, as the collaborators are known, was over.
However, in 2002, under Roh Moo-hyun, prosecution and confiscation of property from the collaborators and their descendants began again. Without getting into details (20 year rule), I would suggest searching for information on Japanese collaboration on the Hankoyreh English website, as well as the Joongang Ilbo. The Hani is a left wing paper, and the Joongang is more of a center-right paper. Between the two, you should get a good idea of what's been going on.
As to Park Chung-hee, he was a member of the Korean military, graduating in the second class of the Korean Military Academy. He was kicked out of the military and sentenced to death for being a communist in the late 40's, escaping execution because of influence from friends of high rank. At the outbreak of the Korean War, he was let back into the military, rising to the rank of Brigadier General by the end of the war. Why was he not prosecuted by the government?
TLDR - the US had no hand in purging Japanese collaborators from Korea, the Korean government, being run by the upper-classes, was loathe to purge Japanese collaborators, also of the upper-classes, with the exception of the most egregious of offenders. It wasn't until the last 20 years that the Korean government, under liberal administrations, really decided to investigate collaboration.
Multi-part answer:
Apologies for resurrecting a topic from so long ago but I came across this thread in a search and frankly I'm more than a little disturbed by the answer you got because it seems to go against quite a lot of the literature on the subject. One cannot say that the US occupation forces in korea played "no part" in regards to collaborators - it's only a question of how much involvement and the reasons for that involvement. They played a key role and it's grossly misleading to whitewash it.
Before I go further though, let me just mention that this is an excellent question. Yes, it does seem rather odd that given the context of korea & japan that a known japanese collaborator managed to get to such a high rank doesn't it? It's not an often asked question, despite how jarring the picture should be, but it highlights just how much there is left to uncover and write on the post-1945 history of korea.
The short answer is that the collaborators were not purged. The US military government not only actively blocked any attempts to purge the collaborators, it also cemented them into political and economic power - meaning that the house cleaning that took place in france could never take place in korea. These issues are still with us at present, for example a catalogue of collaborators was being hindered recently by the conservative government from being published and the question of whether Park Chung-hee swore a blood oath (i.e. committing his life) to the japanese was found at court to be true. In north korea the opposite seems to be the case, most literature agrees that collaborators were purged very quickly and effectively - Bruce Cummings mentions in his book "Korea's place in the sun" that the issue was dealt with to thoroughly that there were japanese technicians who chose to stay in north korea and faced no negative sentiment.
Political background to the occupation
There was a period between the formal surrender of japan to end WW2 and the arrival of US troops in korea. During that time the KPR arose:
With liberation, the Korean peninsula was a tumult of revolutionary waves. Koreans wanted socioeconomic changes by liquidating Japanese colonial legacies. This revolutionary fervor was faithfully reflected in politics. At first, the revolutionaries dominated the political scene by winning the Korean people’s favor. The Committee for the Preparation of Korean Independence (CPKI), led by Yeo Un-hyeong, came to prominence. People in the whole country spontaneously organized people’s committees and these became CPKI branches within ten days of liberation. The CPKI was not a communist organization, but rather a kind of national coalition that included all political forces except the pro-Japanese Koreans. It soon evolved into the Korean People’s Republic (KPR). From 15 August, when Korea was liberated, until 8 September, when the U.S. Army first landed in southern Korea, the CPKI ruled the extent of the country. It virtually exercised its sovereignty in the region.
from "Paramilitary Politics under the USAMGIK and the Establishment of the Republic of Korea" (by Kim Bong-jin) Korea Journal/Summer 2003, pg 291
"Revolutionaries" in the above should be read as people seeking reform and change rather than the more "communist" type of revolutionary.
By the time American troops arrived, Koreans were deeply engaged in activity aimed at replacing the colonial regime and, they believed, establishing their independence. In mid-August Japanese Governor-General Abe Nobuyuki ... [ snipped text about fearing attacks against japanese in korea] ... approached Yo Un-hyong, a non-Communist Leftist whose demands for freedom of action were reluctantly accepted. Thus in Seoul Yo established the Committee for the Preparation of Korean Independence (CPKI) and began setting up a governmental framework for Korean self-rule. At the local level people’s committees sprouted up, often at the behest of the CPKI. These bodies frequently gained backing from native soldiers who had recently deserted the Imperial Japanese Army and armed youth groups (ch’iandae) and private armies that included thousands of prisoners – both political and criminal – freed by the CPKI.
Yo sought to recruit people of all political stripes, but most conservatives refused to cooperate, resulting in a Leftist-dominated organization. Korea in those days, according to one authoritative account, was ‘a maelstrom of old and new classes, political groups, and ideologies’. Four in five natives farmed for a livelihood, overwhelmingly as tenants. Japanese-directed economic development had added to the mix ‘an assortment of capitalists, white-collar professionals, [and] factory wage workers’. Wartime mobilization had produced increasing, often forced, internal migration and a draconian system of assimilation that sought to root out all vestiges of Korean culture, including names and language. While open resistance was impossible, Koreans accommodated their Japanese masters to varying degrees, producing resentments within the native population that promised to surface with liberation.
Broadly speaking, political groupings divided into Right and Left. Most Koreans with property and education had engaged in some collaboration with the Japanese, and they stood on the Right in opposing far-reaching change, such as comprehensive land reform or other instruments for redistributing wealth. Joining them were less educated, less prosperous people who had served in the colonial regime, including in the notorious police force, which was nearly 40 percent Korean.
On the Left were a variety of groups – intellectuals, peasants, workers, and students – who lay in wait to rise up against the government. Groupings were far from static. On the Left the Communists were the best organized and possessed some connection to the Soviet Union through its Seoul consulate, but they were neither dominant nor initially unwilling to work with others.
from "‘An Alliance Forged in Blood’: The American Occupation of Korea, the Korean War, and the US–South Korean Alliance, by William Stueck and Boram Yi, The Journal of Strategic Studies, Vol. 33, No. 2, 177–209, April 2010, pg 183
Effectively, by the time the americans arrived the japanese administration had already been replaced by a coalition covering the political spectrum.
The notable exception are the collaborators and this will become important later on, as will the fact that most of the wealth was controlled by them. Collaboration with the japanese was almost a requirement in order to retain or gain wealth. They formed the Korean Democratic Party (KDP).
As a side note, the labels of Left/Right are somewhat meaningless because collaborators were seeking to retain their wealth rather than fighting for a cause. Putting themselves forward as "anti-communist" and "pro-american" was a way to influence the americans, particularly John Hodge who seems to have been a rabid anti-communist, just like they'd been "pro-japanese" before 1945. The labels "conservatives", "communist rebels", etc get used liberally in most texts about the period but at the time it was basically collaborators vs others. The "communist" label being applied to enemies continues far into the future, for instance the Gwangju massacre was called a "communist uprising", and even today the labels "ppalgengi" (red aka "communist") and the counter of "chinilpa" ("friend of japan" aka pro-japanese) continue to be thrown around in political debate.
This situation would not last of course and that's why I say that "one cannot say that the US occupation forces in korea played no part in regards to collaborators".
Continued in part 2