Japan and the United States was on sooner or later. It’s interesting that FDR was in bed with the Communists and the embargo was a ploy to prevent the Japanese from possibly attacking Russia and presenting Stalin with a two front war. FDR was probably not aware of the ulterior motives of his close advisers.
FDR still had a thing for Uncle Joe after Churchill started preparing for the war to come after WW II.
I don’t think that the embargo was aimed at preventing a Japanese attack on the Soviet Union. The Japanese had already invaded Siberia in 1939 and were soundly beaten, so there was no appetite in Japan for a repeat. Much easier to get resources in SE Asia.