World War II

====Soviet–Japanese border conflicts====
{{Main|Soviet–Japanese border conflicts}}

In the mid-to-late 1930s, Japanese forces in [[Manchukuo]] had sporadic border clashes with the Soviet Union and [[Mongolian People's Republic|Mongolia]]. The Japanese doctrine of [[Hokushin-ron]], which emphasised Japan's expansion northward, was favoured by the Imperial Army during this time. This policy would prove difficult to maintain in light of the Japanese defeat at [[Battles of Khalkhin Gol|Khalkin Gol]] in 1939, the ongoing Second Sino-Japanese War{{sfn|Beevor|2012|p=342}} and ally Nazi Germany pursuing neutrality with the Soviets. Japan and the Soviet Union eventually signed a [[Soviet–Japanese Neutrality Pact|Neutrality Pact]] in April 1941, and Japan adopted the doctrine of [[Nanshin-ron]], promoted by the Navy, which took its focus southward and eventually led to war with the United States and the Western Allies.<ref>{{cite magazine |author=Goldman, Stuart D. |date=28 August 2012 |title=The Forgotten Soviet-Japanese War of 1939 |access-date=26 June 2015 |magazine=The Diplomat |url=https://thediplomat.com/2012/08/the-forgotten-soviet-japanese-war-of-1939/ |archive-url=https://web.archive.org/web/20150629092821/https://thediplomat.com/2012/08/the-forgotten-soviet-japanese-war-of-1939/ |archive-date=29 June 2015 |url-status=live}}</ref><ref>{{cite web |author=Timothy Neeno |access-date=26 June 2015 |title=Nomonhan: The Second Russo-Japanese War |publisher=MilitaryHistoryOnline.com |url=https://www.militaryhistoryonline.com/20thcentury/articles/nomonhan.aspx |archive-url=https://web.archive.org/web/20051124070956/https://www.militaryhistoryonline.com/20thcentury/articles/nomonhan.aspx |archive-date=24 November 2005 |url-status=live}}</ref>