Can any credence be given to Chang's findings below?
After the Marco Polo Bridge Incident,"Japan did not aim to extend the fighting beyond northern China".
And:
page 208Japan's swift occupation of northern China in July posed a direct danger to Stalin.Tokyo's huge armies were now in a position to turn north and attack Russia anywhere along a border many thousands of kilometres long.The year before,Stalin had publicly identified Japan as the principal menace.Now,it seems,he activated a long-term Communist agent in the heart of the Nationalist Army and detonated a full-scale war in Shanghai,which drew the Japanese inextricably into the vast heartland of China---and away from China.
The 'mole' was one Zhang Zhi-zhong,commander of the Shanghai-Nanking garrison.Known as the 'Red teacher' at the Whampoa Military Academy,Zhang asked to join the CCP but was told by Chou En-Lai to stay in the Nationalists as a sleeper.
Zhang is credited with triggerring the Oyama Incident 1937 which Chang infers was authorised via the Soviet embassy.
http://forum.axishistory.com/viewtopic.php?t=82234
Zhang then commenced the Shanghai fighting,including an air attack on the Japanese flagship Izumo,and issued false press reports that the Japanese had attacked first.An all-out war commenced in China....ZZZ staged an incident outside Shanghai airport,where a Chinese army unit,which he imself specially stationed there,shot dead a Japanese marine lieutenant and a private.A Chinese prisoner under sentence of death was then dressed in Chinese uniform and shot dead at the airport gate,to make it seemed the Japanese had fired first.
Moscow was exhilarated by the turn of events,as the Soviet foreign minister,Maksim Litvinov,admitted to French vice-premier Leon Blum.According to Blum,Litvinov told him that 'he and the Soviet Union were perfectly delighted that Japan had attacked China[adding]that the Soviet Union hoped the war between China and Japan would continue just as long as possible..."
This was probably one of Stalin's greatest coup.With just one sleeper he warded off the Japanese threat to Soviet Russia.Both of the Russians who dealt with ZZZ,the military attache Lepin and Ambassador Bogomolov,were immediately recalled and executed.
ZZZ was quickly forced to resign,in September,by an angry Chiang...[but] stayed with the Communists when the Nationalists fled to Taiwan in 1949.
ZZZ can agruably be considered the most important agent of all time.Most agents just passed on information.ZZZ quite possibly altered the course of history virtually single-handedly.