Germany declared war on the USA after Japan attacked Pearl Harbor, fulfilling their treaty with Tokyo.
Don’t forget that Germany was annexing/given territory to prevent another World War. Czechs, Austrians, The Saar, etc.
The False War after 9/1/39 showed how unprepared France and Britan were to back up Poland.
In my opinion, the Pacific War was purley based on economics, and to a lesser degree cultural misunderstandings. The war with Germany was based on ideology, as well as economics. Germany (at the time) was a society based on fear and power worship coming off a humilating defeat of WWI.
As for the USSR, I feel that UK/France knew they could not expect to take down both Germany and the Soviets, thus they “looked the other way” when Eastern Poland was consumed.
America was not conned into war. In my thoughts, FDR knew the dangers of losing democracy if the UK fell.