What is the reason why China did not immediately declare war on Japan after the outbreak of Japan's all-out war of aggression against China?

Internal instability, Chiang Kai-shek was unable to suppress and declare war on Japan at the same time. Jiang believes that Japan is threatened by insufficient foreign invasion, but once the internal invasion becomes potential, its political power will be lost.

Therefore, Jiang was afraid that a war against Japan would greatly reduce the strength of the national army, thus gaining an absolute advantage over * * * in military power and making * * * take the opportunity to gain the upper hand.

At the same time, Jiang thinks that Japanese strength is insufficient, and it has annexed the whole of China, and the more it eats, the more it sinks. Jiang's strategy towards Japan is basically to use China's great strategic depth to stall the Japanese and finally give them a final blow when they are exhausted.

As for strength, it is true that the national army is inferior to the Japanese army in equipment, but its comrades-in-arms are absolutely superior in morale and quantity. In particular, the troops directly under the Central Army of the National Army are superior to the Japanese in strategy and tactics. The armored forces during the August 13th Anti-Japanese War, and later the New First and Sixth Armies in the Burma Campaign, were all China powerhouses that frightened the Japanese. Roosevelt even considered sending Chiang to Europe to participate in the war, but finally gave up because the troops of the national army were defeated in World War I.