Did Nagasaki lead to Korean division?

Did the second US atomic bomb, on Nagasaki, lead to the division of Korea into north and south?

So claims Tim Shorrock on Substack. 

The reality, as I see it? 

Not entirely and not deliberately at the time.

The US/USSR split was intended to be temporary, until a trusteeship. Here's more of its reality:

Soviet troops advanced rapidly, and the U.S. government became anxious that they would occupy the whole of Korea. On 10 August 1945 two young officers – Dean Rusk and Charles Bonesteel – were assigned to define an American occupation zone. Working on extremely short notice and completely unprepared, they used a National Geographic map to decide on the 38th parallel as the dividing line. They chose it because it divided the country approximately in half but would place the capital Seoul under American control. No experts on Korea were consulted. The two men were unaware that forty years before, Japan and pre-revolutionary Russia had discussed sharing Korea along the same parallel. Rusk later said that had he known, he "almost surely" would have chosen a different line. The division placed sixteen million Koreans in the American zone and nine million in the Soviet zone. Rusk observed, "even though it was further north than could be realistically reached by US forces, in the event of Soviet disagreement ... we felt it important to include the capital of Korea in the area of responsibility of American troops". He noted that he was "faced with the scarcity of US forces immediately available, and time and space factors, which would make it difficult to reach very far north, before Soviet troops could enter the area". To the surprise of the Americans, the Soviet Union immediately accepted the division.

See that, Tim? Stalin agreeing, tacitly at least, on the division in general at Tehran and Yalta, and the details in 1945. 

As for the details of August 1945? This.

On 10 August, Soviet forces entered northern Korea. Soviet forces began amphibious landings in Korea by 14 August and rapidly took over the northeast of the country, and on 16 August they landed at Wonsan. Japanese resistance was light, and Soviet forces secured most major cities in the north by 24 August  (including Pyongyang, the second largest city in the Korean Peninsula after Seoul).

There we go. 

In addition, per the 1945 Moscow Conference, North Korea shifted to accepting the trusteeship plan, presumably under "nudging" by the USSR. 

As we advance to 1948, elections were held in South Korea, under US occupation at the time — but under UN supervision. North Korea was offered the opportunity to participate, but Kim Il-Sung, in conjunction with the USSR, rejected that, in part because South Korea had twice the population. 

Yes, Syngman Rhee helped start the Korean War. Yes, the US has a history of war crimes in that war. Yes, the US had a degree of imperialism. But, in this case, unlike Vietnam 1954, it was not the US ultimately at fault for how we got to this point. 

And again, this is why I identify as a skeptical leftist. See also my 80th anniversary piece on both bombs.

Related to that 1948 elections link, note the stories of Kim Ku and Kim Kyu-Sik. Both opposed the South Korean election, knowing it would through a spanner in the wheel of reunification. The former was assassinated in 1949 by a South Korean army lieutenant; speculation continues to this day as to whether or not he acted alone. The latter was kidnapped by North Korea after the start of the war and is presumed to have died in captivity later that year.

Moving ahead to the war? I, like Shorrock, have read Bruce Cumings. I've also read Blaine Harden items he's written about Korean and divided-Korean history, as well as Shorrick himself, whom I follow. If we limit ourselves to the battlefield, the US probably did commit the most war crimes of any Korean War belligerent. If we include prisoner of war treatment, though, North Korea almost certainly moves to the head of the class. 

As for Soviet meddling? Already at Potsdam, per D.M. Giangreco (it's in conference minutes) Stalin was trying to get a protectorate over Italian Libya, because of Italians fighting on the eastern front. Beyond the imperial greed, this was of course rank hypocrisy, as he had been pushing and goading FDR on calling out British colonialism. 

And, despite Turkey staying clearly and cleanly neutral in World War II, Stalin, allegedly pushed by Beria, not only abrogated a treaty over the Straits with Turkey, but pushed to try to take northeastern sections of the country. This backfired, leading to the declaration of the Truman Doctrine, and also to the Marshall Plan offering aid to Turkey as well as Greece, and from there, to the formation of NATO.