I know that the Japanese attacked the US because we stopped supplying oil to them, but its occurred to me that Russia has oil, something I've been told Hitler wanted very much. Why didn't the Japanese, who already had a presence on continent, join the Germans in a pincer-like assault of Russia to see ure the oil that the USSR had? Wouldn't this have been a far more feasible strategy than attacking the US?
Japan and the Soviet Union's client state of Mongolia had a border dispute in 1939. This led to a poorly known, but rather large clash in the summer of 1939. Known as the battle of Khalkhin Gol by the Soviet Union and the Mongolians, or the battle of Nomanhan by the Japanese, this conflict lasted from May until September and was a bloody defeat for the Imperial Japanese Army. They lost around 45,000 men and had two infantry divisions get badly mauled. The Japanese learned that the Soviets had more tanks and better tanks than they did. They had better artillery and a bigger air force. It was also the first victory won by Soviet general Zhukov in World War II.
The Japanese realized their army could not take on the Soviet army in the foreseeable future, so they declined to join the Germans in their attack on the Soviet Union. The German Operation Barbarossa was a big surprise to the Japanese government, who were not consulted in advance. Japan was not legally obligated to join Germany in a war that Germany initiated, so Japan declined to become involved and honored the non-aggression pact they signed with the Soviet Union in 1940. Japanese diplomats made some efforts to get the Soviets and Germans to join them in an alliance against the United Kingdom in 1940, but neither Germany or the Soviet Union showed any real interest in this proposal.
Source: "Soldiers of the Sun: The Rise and Fall of the Imperial Japanese Army" by Merion Harries and Susan Harries (1994)