Part I
When discussing the actions of Imperial Japan in the 1930s, particularly those in China, it can often seem that their actions make no sense, or are otherwise irrational. We often apply the Rational Actor Model (RAM) to state actions, as it is easy to envision states as though they are driven by a singular will, making moves in the Great Game of international politics based on cold, calculating decisions as to what would gain them the most benefit. Yet, as Allison illustrates in Essence of Decision, the RAM is often found wanting when it comes to analysing state actions, and no modern polity illustrates this better than Imperial Japan in the first half of the 20th century.
To say that Imperial Japan had fraught civil-military relations is to put it mildly. The Principle of Supreme Command in the Meiji Constitution made the Emperor commander in chief of the Army and Navy, and the military branches interpreted this to mean that they were answerable only to the Emperor, and not to the civilian government led by the Prime Minister. To add on to this, the principle that Army and Navy ministers had to be active duty officers essentially gave both branches of the military the ability to bring down the government if they so choose. To put it mildly, Imperial Japan had no grand strategy for national defense, no joint planning meetings between the Army, Navy, and civilian government to determine how best to employ Japan's resources and set a singular policy for the nation. Rather, the Army and Navy each made demands for the resources they thought would be necessary for their war with their envisioned future enemy: the Soviet Union for the Army, and the United States for the Navy almost entirely independently from each other, without input from the civilian government.
Even more so, within the Imperial Japanese Army, the Kwantung Army--the formation deployed first to Southern Manchuria had a reputation for emulating the principle of gekokujō which roughly translates as "rule from below", and generally represented the usurpation of authority from those bodies that were supposed to be making decisions by individuals and groups that were ostensibly much lower down the chain of command. This had manifested in 1931, when a group of midlevel staff officers orchestrated the Mukden/Manchuria Incident, where a false-flag attack resulted in the Kwantung Army rapidly overrunning much of Manchuria, with the government unable to reign in the army, at least partially due to complicity between Kwantung Army, the Army Ministry, and the IJA General Staff. Later on, the Marco Polo Bridge Incident of 1937 would see escalation by local commanders, followed by further deployment of more IJA troops from Korea, Manchuria, and Japan to China that would ultimately escalate into the Second Sino-Japanese War. In the context of Khalkin Gol, the important take away from these two--perhaps more well known--incidents is that neither was an operation concocted by high level officers in Tokyo then distributed to field forces for execution. Rather, each was the result of a field force taking action, and the General Staff, Army Ministry--and ultimately the government--following behind them. In this way, Captains and Colonels in the field were effectively shaping policy for all of Japan.