Das ergibt für mich keinen Sinn, die hätten doch wissen müssen das Sie keine Chance hatten, ein zwei Fronten Krieg gegen die Sowjetunion war doch realistischer.

Man hatte es versucht und 1938/39 gegen die Sowjets mehrfach recht deutlich verloren

Battles of Khalkhin Gol - Wikipedia

While this engagement is little known in the West, it played an important part in subsequent Japanese conduct in World War II. The battle earned the Kwantung Army the displeasure of officials in Tokyo, not so much due to its defeat, but because it was initiated and escalated without direct authorization from the Japanese government. This defeat combined with the Chinese resistance in the  Second Sino-Japanese War, ^[67] together with the signing of the  Nazi-Soviet non-aggression pact (which deprived the Army of the basis of its war policy against the USSR), moved the Imperial General Staff in Tokyo away from the policy of the  North Strike Group favored by the Army, which wanted to seize Siberia for its resources as far as  Lake Baikal. ^[68]

Instead, support shifted to the  South Strike Group, favored by the Navy, which wanted to seize the resources of Southeast Asia, especially the petroleum and mineral-rich  Dutch East Indies.  Masanobu Tsuji, the Japanese colonel who had helped instigate the Nomonhan incident, was one of the strongest proponents of the  attack on Pearl Harbor. General  Ryūkichi Tanaka, Chief of the Army Ministry's Military Service Bureau in 1941, testified after the war that "the most determined single protagonist in favor of war with the United States was Tsuji Masanobu". Tsuji later wrote that his experience of Soviet fire-power at Nomonhan convinced him not to attack the Soviet Union in 1941. ^[69] On 24 June 1941, two days after the war on the  Eastern Front broke out, the Japanese army and navy leaders adopted a resolution "not intervening in German Soviet war for the time being". In August 1941, Japan and the Soviet Union reaffirmed their neutrality pact.

Anlass war dann das US Ölembargo.

Die Idee war, möglichst viel Territorium zu besetzen und den Preis für die Rückeroberung so hoch wie möglich zu treiben.

Man hoffte, dass die Amerikaner nicht bereit sein würden, einen hohen Preis zu zahlen und man in einem Verhandlungsfrieden einwilligen würde.

Natürlich verbaute man sich das mit dem Angriff auf Pearl Harbor, der in den USA zur Bereitschaft führte, den Krieg bis zum bitteren Ende zu führen.

Den konnte Japan nicht gewinnen.

Grim Economic Realities (combinedfleet.com)