I want to know the answer to the following question:
In 1939, what caused nearly 2 million Koreans to be forced into the labor force or the army?
All the background I'm provided with is that "Conscription of Koreans for labor in war industries began in 1939, with as many as 2 million Koreans conscripted into either the Japanese Army or into the Japanese labor force.". Is that enough to answer the question?