The Second Sino-Japanese War and the starting date of World War II

by LordKalithari

As far as I know, the Second Sino-Japanese War is considered to be a part of the second World War. Why then is it often said that WW2 started on September 1st, 1939 instead of July 7th, 1937?

Is it because it only became a true world war in 1939 since previously combat was limited to Asia or is there another reason?

hellcatfighter

Hiya! I've answered a similar question here.

TLDR:

Is it because it only became a true world war in 1939 since previously combat was limited to Asia

This.