The resource logic of Japan's northern strategy

Why did Japan consider a northern strategy against the Soviet Union after Khalkhin Gol?

Siberia offered oil and other resources, while striking north appeared to avoid the immediate war with the much stronger British and American powers that a southern advance risked.

The northern option was meant to solve Japan's resource problem through territory in Siberia. It also offered a way to avoid provoking Britain and the United States, whose power made a direct war unattractive. Western Siberian oil, gas, minerals, and iron resources were known and at least partly exploitable with contemporary technology. Japanese grand strategy therefore followed the geography of resources rather than treating north and south as arbitrary directions.