British cooperation may turn Japan north

Would Japan pursue a northern or southern strategy under a continuing Anglo-Japanese alliance?

A northern strategy against Russia becomes more plausible if alliance ties expose Japan to British armored doctrine and keep the southern maritime powers friendly.

British interwar exercises generate unusually strong evidence about tank doctrine because Britain has enough equipment to test ideas at scale. German theorists had ideas of their own, but lacked tanks for comparable large exercises. British tests supplied practical evidence, although they were organized around British theories and did not perfectly match other armies' needs. Closer Japanese access to the exercises might improve its armored forces and make a northern resource strategy more credible. A move against Soviet power in Siberia could attract British and American support instead of provoking the coalition created by Japan's historical southern advance.