There have been a number of books suggesting that FDR was quite concerned about getting the US into WWII as soon as possible, Rig (and for quite cogent reasons, by the way...he was worried that the Germans might win in Europe). I can't think of the titles...I read most of them, oh, maybe fifteen or twenty years ago. Anyway, from his point of view it was imperative to get the USA in the war before a total German victory in Europe occurred, and the Germans were looking very strong in 1941.

He had a problem, though. Germamy had no reason and no motivation to declare war on the USA. Furthermore, the American public and Congress were not showing any enthusiasm for getting into a war in Europe, and the Germans were not offering any significant provocations, despite the fact that FDR was doing everything he could to help England in the Battle of the Atlantic, short of actually going to war. For example, the Americans unofficially contributed long range scout planes to help the British track the Bismark in the spring of '41. They did other things to help the British locate German U-boats at sea. And they supplied the British with a whole bunch of older American destroyers for convoy escort...free!

However, the Germans had utterly no good reason to get in a war with the USA, so they didn't....for the time being.

The only feasible way for FDR to get an isolationist public and Congress onside for a war was for someone to launch an outright and apparently unprovoked attack on the USA. (think 911...for instance)

And who would do that? Well, the Germans wouldn't...and there was no way to maneuver them into doing so. But the Japanese would...provided the USA cut off their overseas supplies of two vital commodities: oil and steel. Roosevelt effectively did that in early '41 with an embargo.

The Japanese had been tied down since the late 30's in a major war in China. They could not continue to prosecute that war without using up massive amouts of oil and (secondarily) steel. They had only enough oil in reserve to keep their navy and other services going for about 1 year...and no domestic sources of oil.

When FDR put the embargo in place, war with Japan became inevitable.

It's possible that FDR did not expect the Japanese to have the expertise to do such a long range attack as their raid on Pearl Harbour. He may have been expecting them to hit farther west only...in the Phillipines and Southeast Asia. Well, they hit there AND at Pearl Harbour, and proved to be much more capable than anyone in the American high command (except Claire Chennault) would have guessed. Chennault commanded the American Volunteer Group in China (the Flying Tigers) and he was well aware how good the Japanese air force was...but no one in the USA would listen to him! The Zero fighter was the best fighter in the Pacific (maybe in the world at that time) and Chennault knew it, but he was not believed back in the USA. The Japanese navy was also the best in the world in late '41 in a number of respects. Nobody in the USA believed that either.

Accordingly, they got caught with their pants badly down for about 6 months by the Japanese...until the battle at Midway where Japanese luck ran out with a vengeance!

FDR had good reason to want to go to war against Germany. His best way of doing so was to trigger the war with Japan, after which it wouldn't be too hard to enlarge an existing conflict...it never is. Hitler then made the incredibly stupid error of immediately declaring war on the USA after Pearl Harbour instead of just standing aside (which he could have) and letting the Japanese twist in the wind. They didn't help him against Russia, so why would he help them against the USA??? It boggles the mind!

Anyway, Roosevelt calculated cleverly, in my opinion, and he got his 2-front war when he wanted it...and won it handily, which was virtually inevitable given the combined GDP of the USA, Russia, and Great Britain.

I'm not judging him one way or another for doing it...I'm just saying: that's what he did. He deliberately pushed the Japanese into a corner so they would go to war against the USA.

He may have been quite shocked at how much damage the Japanese Navy (Naval Air Force) did at Pearl Harbour and elsewhere though. I expect he was. After all, the consensus stateside before Pearl Harbour seemed to be that the Japanese flew planes made out of rice paper that were extremely inferior copies of obsolete American planes. Nothing could have been farther from the truth...!