In 1938 and 1939, the Kwantung Army occupying Manchuria was severely defeated by the Red Army over a border dispute. Eager to score a victory, the Imperial Japanese Army was engaged in the border dispute near Khasan, where the borders of Manchuria, Korea and Siberia meet. Thinking they would defeat the Soviets easily, the Japanese did not know that the numerically equal Red Army had superior numbers of tanks, aircraft, and artillery.
A year later, near Nomonhan, China, the Red Army and the Kwantung Army again clashed. Russian Lieutenant General Georgi Zhukov, who would go on to lead the Red Army against the Nazis, executed very effective attacks on the Japanese after ordering up T-34 tanks and superior numbers of aircraft to the front.
What is significant about the Border incidents is the Japanese Army's rush to fight. Mikiso Hane, in his book Modern Japan, calls the Kwantung Army's actions evidence of “self-delusion.” The Army did not learn anything from its border wars in China. The bravado was evident when the Japanese Army pushed to attack the United States and Great Britain.
A cease-fire was arranged in September 1939, after Hitler and the Soviet Union invaded Poland. The Red Army didn't want to be tied down to a two-front war. The Japanese committed 56,000 soldiers and lost 8,400. The Soviets and the Mongolians lost 9,000.