How come the United States didn't have/enforce a trade embargo with Nazi Germany, especially after the US entered WWII?

by Im_Nick_Saban

It is widely noted how big US companies traded with Nazis all the way through the 30s and 40s, but how come the US didn't stop any of these transactions?

ParkSungJun

Can you please clarify where it is "widely noted" how big US companies traded with Nazis through the 30s and 40s? This is an allegation I have usually seen in reference from conspiracy theories, typically either Illuminati related or anti-Semitic.