Someone doesn't know their history. its you. Look at the wars america was in before 1940. For example- the Spanish-American war. Basically caused because we wanted some of Spain's stuff in the Carribean, and trumped up on an explosion in port that ended up being an accident.
The Mexican American war- because we wanted to move our southern border to the Rio Grande.
The War of 1812- multiple causes and may have happened anyway, but at least part was a desire to annex Canada.
The Indian Wars- all undeclared, but we took each tribe's land one at a time.
The US has been an imperialistic war monger from the beginning. We just kept it to our own continent until the 1900s.