From the 1988 article 'The Origins of the Pacific War' in the Journal of Interdisciplinary History:
Which was more accurate: the view that the United States was unlikely to go to war over European colonial possessions, or the [Japanese] navy's position that American intervention was too probable to make the "southward advance" an advisable policy? If one examines the available evidence, it is difficult to avoid the con- clusion that the United States would not have gone to war in the summer of 1940 had the Japanese restricted their attack to the British and Dutch colonies. Unbeknown to Tokyo, on 23 May 1940 the United States' senior political and military officials re- viewed strategic policy in light of the anticipated German victory against France and determined (according to General George Mar- shall's notes of the meeting) that "we must not become involved with Japan, that we must not concern ourselves beyond the I 80th meridian, and that we must concentrate on the South American situation."
The Roosevelt administration, nonetheless, sought to prevent Japanese expansion into Southeast Asia through the use of the two diplomatic tools it had available to influenceJapan: the threat of an oil embargo and the threat of military intervention. After considerable debate and confusion, the administration decided in July 1940 not to impose an oil embargo on the grounds that such a drastic step might provoke the very action-a Japanese attack on the oil fields of the Dutch East Indies-that the United States sought to deter.l"ith respect to military threats, however, the United States was willing to let the Japanese believe that the United States Navy was poised to interfere in any Japanese move south. 111 May 1940, the United States fleet was ordered to remain at Pearl Harbor rather than return to its regular, less vulnerable bases along the West Coast. The private expla~lationgiven for this action, by Admiral Harold Stark, chief of naval operations, to Admiral James 0.Richardson, the commanding officer, de- serves to be quoted at length:
Why are you in the Hawaiian area?
Answer: You are there because of the deterrent effect which it is thought your presence may have on the Japs going into the East Indies . . .
. . . Suppose the Japs do go into the East Indies? What are we going to do about it? My answer to that is, I don't know, and I think there is nobody on God's green earth who can tell you.
I would point out one thing, and that is even if the decision here were for the U.S. to take no decisive action if the Japs should decide to go into the Dutch East Indies, we must not breathe it to a soul, as by so doing we would completely nullify the reason for your presence in the Hawaiian area. Just remember that the Japs don't know what we are going to do, and so long as they don't know, they may hesitate or be deterred.
edit: It's fine that people are responding to the overall argument of the article (the Japanese decision to attack the US was rational), very interesting comments so far. I'm curious about the quoted section though: does the best available evidence suggest that the US would not have gone to war with Japan had Japan merely conquered British and Dutch colonial possessions?
While there are certainly valid points raised in his article, the fact remains that there are certain points that were not available to Western scholarship for quite some time until recently. For instance-the real doctrine of the Japanese military and their overall defense strategy, the anti-Western and anti-American in particular attitudes of the military officers that ran the country, and the economic details that people skimp on in order to make broad soapboxing points.
For instance, it should be known that just a few months before the war, a Gallup poll found that a sizable majority of Americans (some 60%+) were supportive of actions to stop Japan's aggression through Asia, even if it resulted in war. This is while they were still opposed to intervening in the war in Europe.
Another key point that the author neglects is the importance of scrap metal to the Japanese war economy. While the author attempts to pass it off as being a minor, symbolic sanction, the truth of the matter is that scrap metal, because it has a high quality of iron, was a key part of Japan's war machine for making things like rifles and bullets. As you can see in this chart here, after the start of the 1937 Sino-Japanese War, scrap metal demand increased heavily up until it was blocked in 1940. Petroleum was extremely important, but the fact is that petroleum use in the actual Sino-Japanese war was relatively mild compared to the rapid consumption of refined metals that Japan was burning through at a massive rate. It was such that during some of the initial landings in the Dutch East Indies, Japanese ships were ordered to conserve ammunition and not provide fire support for amphibious landings, resulting in heavy casualties among the landing troops.
Another point that the author neglects was the importance of a defense perimeter in Japanese strategic thought. The idea was to create a Japan that could sustain autarky in Asia, using the resources of the "Southern Resource Area." This SRA and the route to Japan would be protected by a defensive perimeter of airbases.
The problem with this strategy was that the Philippines was in the way. The Philippines could serve as a major base for aircraft and submarines to disrupt the flow of resources between the SRA and the Home Islands. It was a dagger pointed at the potential lifeline of Japan, and even if the US chose to do nothing, Japan could not afford to do so. The possibility of say, British and Dutch submarines operating out of an ostensibly neutral Philippines to strike Japan's already stressed and overwhelmed merchant shipping fleet was too great for Japan to ignore it.
The author attempts to portray Japan as being a rational actor in the war that was prompted by US foreign policy in the region. While this is certainly an improvement over the "utter madness" that he writes about in contemporary newspapers, he handwaves the entire China theater (which is an unfortunately common flaw in most Western analyses of the Pacific War) as well as an understanding of Japanese economic and military strategy (which he cannot be blamed for as our understanding has changed greatly in the past 20 years).
So this is a hypothetical question, I feel, and might be better suited to /r/historicalwhatif.
IR Theory (what the linked article is mostly discussing) has to indulge in hypotheticals to some extent, but this sub has a rule against it that we try not to break too often.
For what it's worth, I thought the article's citations and facts were consistent with what I've read other places. Although I agree with /u/ParkSungJun that recent scholarship has provided some facts not available in 1988.
Ultimately, predicting what a decision maker like Roosevelt might have done in a hypothetical situation in 1940 is perhaps a question that will never be resolved. His speechwriter, Robert Sherwood, once claimed FDR had a "Heavily Forested Interior" which none of his contemporary colleagues breached and will likely mean there will never be a consensus among Historians (or International Relations Theorists) about how he might have reacted to a given situation. It can be tough enough to figure out what he actually did (and why) in the situations that actually occurred.
