Plausable Deniability

The article summarises the general facts but glosses over the more compelling reasons why the belief of prior knowledge exists.

In the first instance, the article doesn’t discusss why the US was in negotiations with Japan, nor why the Japanese diplomatic ciphers (purple etc) were broken.

A quite reasonable explanation for the war between the USA and Japan is that the USA forced Japan into it. The US used coercive negotiations calculated to create an impossible situation for Japan in order to gain economic and political advantage. They did this using all diplomatic and spying resources available. Routine reading of all top level Japanese diplomatic cables was part of this process. The US knew exactly how far Japan would go, and then pushed just that much harder.

Given the ability to predict and partially direct the Japanese response, the US was clearly in no doubt about the eventual outcome, a state of war between the US and Japan.

Why the US did this is better left to students of mid-century geopolitics. That they did do this is in no doubt.

Regarding prior knowledge of the Pearl Harbour attack, there is less evidence. But at the very least the US was expecting some attack on itself. It was in fact quite reasonable for them to expect this, as it created an impression of the US being a victim rather that an agressor.

There also is the possibility that the US did in fact know precisely what was going to happen, but did nothing for fear of compromising their intelligence sources.

Perhaps the US did not expect such a dramatic reaction, but they did expect some reaction. They also expected that reaction to create a massive wave of support for the Goverment in prosecuting war against Japan, and also Germany. They got what they wanted.

Pearl Harbour can only be listed as an event deliberately created by the US, but not necessarily one they expected.


We need to be a trifle careful here. The Staff Report was focused on whether President Roosevelt was aware of the impending attack on Pearl Harbor and did nothing to stop it.

The broader question that you have raised – whether the U.S. goaded Japan into war at all – is more suited for the Great Debates forum than for this forum. You site no evidence for your opinions, which (in summary) seem to be that the U.S. is a capitalist aggressor, plotting and conniving and minipulating poor innocent peace-loving Japan.

That makes for an interesting topic in Great Debates, but I would like to head it off here, and keep the discussion here limited to the question of whether Roosevelt knew about the attack on Pearl Harbor in advance. You may say that this is “glossing over” the broader “facts,” but as Moderator of this forum, I think your post puts one toe over a grey fuzzy line, and is therefore more suitable for Great Debates forum. You are welcome to open your topic there.


Agreed, with some reservations- the main hope of US diplomacy was to put Japan in a make-or-break situation: either Japan gives up on war with Britain/China/Netherlands/France/Etc., or Japan goes to war with the US as well. So one can certainly say that US diplomacy manuevered the situation into war, but I disagree with the implication that the US wanted war more than anything else- they wanted peace, but felt that threatening war was the best way to acheive peace.

I would actually state “no evidence”.

I agree that the US desired Japan to make the first strike (I quoted General Marshall as basically stating such). However, that does not mean they necessarily expected the December 7th attack to be against the US; Japan was also fighting plenty of other countries at the time, and many in Roosevelt’s cabinet and in the armed forces felt that Japan would not move against the US until the formal declaration of war had been made. In fact, Japan’s plan was to make the formal delcaration a scant hour or two before the actual bombing raid, but bureaucratic snafus delayed the delivery of the declaration until after the raid had taken place.

No. There is no evidence that intelligence sources of any type pinpointed the attack as being against Pearl harbor. There is also no evidence that Roosevelt or any of his cabinet knew where or when the first attack would be. They had reasonable expectations it would come on the 7th, but the attack on the 7th could also have been against any number of enemies.

In the sense of “the US manuevered Japan into either declaring war on the US or making peace with all of its opponents”, yes, the US created the event. In the sense of “Roosevelt could have defended Pearl Harbor, but chose not to so that the US would be surprised and scared by the Japanese attack” (which is the main point of the article), absolutely not.

John (SD Staff Corrado)

I must admit I am curiously amused by your separation of topics.

On the one hand, we have the conspiracy theory that the US president knowingly let a major part of his fleet be destroyed and thousands of men killed, in order to promote a war that was being resisted by a significant part of the nation.

On the other hand we have the theory the USA played hard politics to gain advantage in an area it considered it’s personal property (The Pacific).

One is a fanciful topic for loonies, the other is par for the course. I’m just confused as to which is which.


I’m not too anal compulsive about separation of topics, and John has chosen to engage, so let it roll.

My main concern is that this forum be limited to factual type of discussions, rather than political tirades. John’s post is a good example. Your initial post left me uncertain, since it can easily be read as political tirade (“The U.S. was the nasty, aggressive, capitalist, imperialist oppressor, responsible for starting WWII against peace-loving Japan.”)

I have no problem with a discussion here of whether U.S. diplomacy was manipulative. {/Moderator hat off]

My own contribution: I’d be surprised to find any country whose diplomacy didn’t involve manipulation in one form or other. It was perfectly sensible for the U.S. to be delivering ultimatums (however couched) to Japan, to try to get them to back down from their escalating aggression.
Diplomacy and negotiation is all about applying persuasion and pressures to obtain desired results.

The US government knew prior to the attack that war would definitely occur. Mostly this was from diplomatic intercepts using MAGIC.
In the week prior to Pearl Harbour, comments by Under Secretary of State Welles (on reading a MAGIC intercept) indicate that war was inevitable and would occur very soon. At the same time the president asked his naval attache Beardall about when war would break out and got the answer ‘Most any time’

Given these documented expectations of war in the days preceeding Pearl Harbour, it is very surprising that the US fleet was not put onto a state of high alert. The Japanese were pleasantly surprised that no air cover was operating at Pearl Harbour, nor any barrage ballons flown.

If nothing else, the awareness of imminent war and the total failure to put the forces on alert creates the impression that the President expected and perhaps wanted an attack on some part of his forces.

In this context, it doesn’t seem particlarly relevant that he did or did not know specifically about an attack on Pearl Harbour.


And I return you again to the statement by George Marshall that the United States wished Japan to strike the first blow. The U.S. was expecting a strike, it just didn’t know where that strike was to occur, and as I’ve shown, when the list of possible targets was brought up, Pearl Harbor wasn’t considered a likely target. Defenses were prepared at Manilla because the Phillipines were seen as the next object of Japanese aggression; the thought of a sudden raid to hit the fleet stationed at Pearl Harbor was not seriously considered.

Okay, refresh my memory. What are we debating? My article was written to dispel a single myth- that Roosevelt knew an attack was coming specifically at Pearl Harbor, but chose not to allow Pearl Harbor to defend itself so that the United States would be shocked into war with Japan.

You seem to be arguing that the United States knew some attack was coming. I agree, they did. But as I said before- the Pacific is a big place, and there was no indication as to who was going to be attacked, nor what type of attack it would have been. The United States responded by trying to defend the area it thought likely to be attacked (the Phillipines) and did not put up many defenses in the area it didn’t think would be attacked (Pearl Harbor).


jezzaOZ wrote:

You mean a message like this?

This message was sent from the Navy Department on November 27th to all Navy commands, including Pearl Harbor.

While it is possible to fault Admiral Kimmel and General Short for their defensive preparations, as they were in court martial, the message is a clear indication from Washington to the relevant military commands that war was imminent. Neither Kimmel nor Short were specifically instructed as to what defensive preparations to make. Short assumed that sabotage was the most likely threat and gathered airplanes in well guarded locations, unfortunately this made them easy targets. Kimmel stepped antisubmarine patrols, sent out submarine pickets and initiated air patrols, all, again unfortunately, in the wrong places. Whatever blame for the defensive preparations at Pearl Harbor falls on Kimmel and Short, not Roosevelt.

As for the fourteen part message Japanese diplomatic message, you’ll find that even the supposedly damning 14th part, never uses words like ‘ultimatum’. And you’ve avoided answering John Corrado’s important point that while the US was reading Japanese diplomatic traffic, that diplomatic traffic did not give any indication of what targets were to be attacked or when. The Pacific is a very big ocean.

I’d make two objections to Corrado’s fine debunking of Pearl Harbor myths. First, at least one carrier, the USS Enterprise, should have been in Pearl Harbor on the morning of December 7th. The Enterprise was delivering planes to Wake Island and was delayed by a storm and so missed the attack. Second, it’s easy to forget that it wasn’t only Pearl Harbor that was attacked on December 7th or 8th (depending on what side of the international date line you’re on). Other targets included: air attacks on US bases in the Phillipines, Malaya invaded, Hong Kong attacked by ground troops, air attacks on Wake, Guam, Tarawa, and Makin attackes within days of Pearl Harbor and landings in Borneo on December 15th.

With that much military activity, it would be easy to fall prey to focusing on the military threat that was perceived, and in fact the US was aware of some of these attacks, specifically the Malaya invasion force. There is plenty of historical evidence that the Malaya invasion fleet preoccupied US leaders, including Roosevelt, and may have led them to be less proactive in defensive preparations elsewhere.

Andrew Warinner

I’ve read a few books on this subject, and probably the single best one is Gordon Prange’s “At Dawn We Slept.” It’s not a quick read by any means – although the style is very readable – but it’s comprehensive. Prange was one of the world’s great detail freaks. Over a period of decades he interviewed all the principal survivors of the attack on both sides (he lived in Japan off and on and was fluent in Japanese) as well as doing massive documentary research. In fact, he still hadn’t finished the research to his own satisfaction when he died. Two of his assistant researchers then edited his manuscript down from many volumes into a single book. (Same deal with his sequel, “Miracle at Midway.”)

The conspiracy theory is discussed directly by the assistants in an appendix, but IMHO it’s better to read the actual day-by-day buildup to the attack first for context. My impression, reading it, was that Prange is kinder to Kimmel and Short than they objectively deserve. While a few pieces of information they should have had (communique asking for effectively a grid of Pearl Harbor and locations of ships within it) didn’t get to them, it was clearly their duty to have their commands prepared for the worst when pretty much the entire world was at war. Who the heck did they think the Pacific fleet was out there to fight in 1941, Australia? Defending Pearl Harbor against an attack had been a standard war game scenario for decades.

If K & S had been on the ball (not that they were the only ones napping at the switch – compare MacArthur’s behavior at the same time despite his personal legend-building) then the attack would still have happened but it could have been a victory, or even a relative stalemate, rather than a massacre. Either of which would have triggered a declaration of war, without endangering the fleet. Roosevelt didn’t tell K & S to skimp on aircraft recon, or to run their radar only a few hours a day, or park the aircraft in nice neat rows, or to lock up the antiaircraft ammunition to protect it from sabotage; that was all their own doing.

Frankly, Pearl Harbor could have been far worse if Nagumo had taken another attack run or two at base infrastructure and tank farms – as Genda was urging him to do. Fortunately, the bad luck in terms of command weakness wasn’t all on one side.

Blue Fenix wrote:

I dunno. That’s the problem with historical counterfactuals, they didn’t happen.

I can hypothesize a couple of outcomes that would have been worse from the US perspective.

Counterfactual 1: Admiral Kimmel is on the ball and detects Kido Butai before Pearl Harbor is attacked. Kimmel sorties US fleet without the carriers Enterprise and Lexington. Nagumo chooses to engage US fleet (a debatable stipulation, though Nagumo’s orders did state he should do so under some conditions) and sinks most it. In this scenario, the US loses major fleets in blue water, unlike the battleships sunk in Pearl Harbor that were recovered and repaired relatively quickly.

Counterfactual 2: Admiral Kimmel is on the ball and detects Kido Butai before Pearl Harbor is attacked. Kimmel sorties US fleet with Enterprise and Lexington. Nagumo attacks and sinks Lexington and Enterprise. This is worse because it leaves the US with one carrier in the Pacific for a long time, though carriers could have been recalled from the Atlantic.

Counterfactual 3: Admiral Kimmel is on the ball, detects Kido Butai, sorties and engages. Nagumo hightails it home without significant damage to the US fleet. The temptation in this situation would likely have been overwhelming to commit the Pacific Fleet in the defense of the Philippines (after all, that is what the war plans said we should do) where it would have as badly defeated as the US Asiatic Fleet was with the possiblity that up to three US carriers could have been lost.

Kimmel and Short both have their supporters that say they got a raw deal, though it’s difficult to shed too many tears over their lost careers compared to lost lives. As I pointed out, Kimmel did take steps to prepare for a fleet engagement, though they didn’t work out. Both Kimmel and Short fell victim to the classic military blunder of preparing for they attack they expected to come instead of preparing for the attack the enemy could deliver.

Andrew Warinner

Blue Fenix wrote:

I’ve seen that argument put forward many times and by many authorites, including Nimitz, but I’ve never been entirely convinced by it.

Suppose that the tank farms were destroyed, but there was no pipeline running to Pearl Harbor, right? POL would have been delivered by tanker, right? What’s to stop the Navy from docking the tanker and using it as a floating tank farm? [Yeah, I know a tanker doesn’t have the distribution network that a tank farm does, but it would work as a temporary measure.] [Yeah, aviation spirit would been more problematic but not impossible to overcome.]

Base infrastructure like drydocks would have been more valuable, even though the US Navy frequently sent units back to San Diego and San Francisco for repair. On the other hand, if the Yorktown hadn’t been repaired in Pearl Harbor, it wouldn’t have available for Midway and <insert your pet what-if scenario here>.

Andrew Warinner

Stoid is strangely silent on this, isn’t she?

Roosevelt knew war was imminent and Pearl’s exposure was a result of many blunders, as mentioned above and others (a warning sent - and delayed in transit - via commercial Western Union; a duty officer choosing to ignore the test radar crew’s detection of the Japanese, thinking it was a flight of B-17s due in from the mainland).

FDR most assuredly did want to maneuver the Japanese into firing the first shot; I must say the requirements of leadership seem to me to include, if in your perception war is inevitable, motivating the public to rise to the occasion. Vietnam is the obvious example of a what can happen if you try to wage war w/o the public’s resolve.

Despite a successful war game attack on Pearl a few years before, that was a double for the real thing, Washington was not expecting the strike at Pearl. The Orange war plan anticipated the first encounter in the Philippines. FDR and crew were arranging their provocation trip wire in the USS Lanikai, a schooner equipped w/a cannon and some machine guns that was ordered to sail to Indochina in early December 1941. The idea was basically to draw fire on a “bona fide” but quite expendable United States naval vessel from whatever unit(s) of the IJN could be found. The idea was predicated on the intense public reaction, during the buildup in December of 1937 to the Japanese’ rape of Nanking, to the sinking of the USS Panay. Anyway, the Lanikai was putting to sea out of Manila on the morning of Dec. 8 (Dec. 7 at Pearl), and the mission became moot.