Preview: Was Pearl Harbor an inside job?

Summary

History Extra Podcast: "Preview: Was Pearl Harbor an Inside Job?"

Episode Overview

In this compelling episode of the History Extra Podcast, titled "Preview: Was Pearl Harbor an Inside Job?" released on July 4, 2025, host Rob Attar delves into one of the most enduring conspiracy theories in American history: the possibility that President Franklin D. Roosevelt had prior knowledge of the Japanese attack on Pearl Harbor and may have facilitated it to galvanize the United States into World War II. Joined by Pulitzer Prize-winning journalist and author Steve Toomey, the discussion provides a nuanced exploration of the events leading up to December 7, 1941, and evaluates the validity of the conspiracy theories surrounding the infamous attack.

Introduction to the Conspiracy Theory

The episode kicks off with Rob Attar introducing the new series, "History's Greatest Conspiracy Theories," which aims to investigate some of the most pervasive and intriguing historical conspiracies. In the premiere of Season Two, the focus is squarely on Pearl Harbor—a day that shook the United States and changed the course of world history.

Setting the Historical Context [03:02]

Rob Attar sets the stage by recounting the events of December 7, 1941:

"On 7 December 1941, a day that would live in infamy, Japan attacked the US naval base at Pearl Harbor, killing more than 2,400 people, sinking a number of ships and destroying dozens of aircraft. It's one of the most notorious surprise attacks in history." [03:02]

This dramatic attack precipitated the United States' entry into World War II, transforming it from a policy of isolationism to active involvement.

Tense US-Japan Relations and Negotiations [04:05]

Steve Toomey provides a detailed account of the geopolitical tensions between the United States and Japan leading up to the attack:

"The attack occurred at a time of incredibly tense relations between the United States and Japan. For months the two sides have been negotiating about how, my phrase, to get Japan to behave better." [04:05]

Despite the simmering tensions and Japan's aggressive expansion in Asia—evident from its actions in China and Indochina—both nations were engaged in diplomatic negotiations aimed at peaceful resolution. However, unbeknownst to many, Japan had already committed to a path of war in the Pacific, making the attack on Pearl Harbor a calculated move rather than an impulsive act.

Expectation of War and Intelligence Gatherings [05:34]

Rob Attar probes the extent to which the United States anticipated the attack:

"The United States expected war in the Pacific any minute. ... Franklin Roosevelt expected war. The American Navy, the American army expected war. What they didn't expect is where it actually also broke out." [05:34]

This highlights that while the U.S. government was on high alert for potential conflict, the specific target of Pearl Harbor was unforeseen. The intelligence community was aware of Japan's expansionist ambitions, but pinpointing Pearl Harbor as the exact target remained elusive.

Breaking of the Japanese Diplomatic Code [07:18]

A crucial aspect of the discussion revolves around U.S. intelligence capabilities at the time. Toomey explains:

"The US had broken... the Japanese highest level diplomatic code... They were reading Japanese diplomatic messages in real time." [07:18]

This breakthrough provided the U.S. with significant insights into Japan's intentions. However, the intelligence gathered was broad and did not specify the exact nature or location of the impending attack. The messages merely indicated that Japan was poised for major actions in the Pacific, aligning with the observed movements of Japanese naval forces toward key strategic areas like Malaya, Singapore, Indochina, Indonesia, and the Philippines.

Limitations of Intelligence: Naval Codes Remained Unbroken [07:35]

Despite the successes in diplomatic code-breaking, the most critical Japanese military communications remained undeciphered:

"The Japanese naval code... was not read by the United States... It broke that code... after the war had started." [07:35]

This meant that while the U.S. had a general sense of Japan's aggressive posture, the specific plans, including the attack on Pearl Harbor, were hidden. Thus, the element of surprise was maintained, making a coordinated defense against the attack significantly more challenging.

Assessing Preparedness at Pearl Harbor [09:46]

Attar raises a pivotal question regarding the preparedness of U.S. forces at Pearl Harbor:

"Had the US Authorities been warning bases such as Pearl harbor of potential attacks and encouraging them to be prepared?" [09:46]

Toomey responds affirmatively, indicating that based on the intelligence available, U.S. authorities were actively preparing for possible Japanese aggression. This included not only diplomatic maneuvers but also practical measures to ready military bases for potential conflict.

Conclusion and Implications [10:04]

The episode concludes by emphasizing the distinction between general awareness of impending war and the specific intelligence required to predict the exact timing and location of an attack. While the U.S. was undoubtedly bracing for war in the Pacific, the lack of precise information about Pearl Harbor meant that the attack retained its element of surprise.

"Simply being told that something big was going to happen very soon, didn't say Pearl Harbor. It comported with what seemed to be the plan of the Japanese..." [07:18]

Final Thoughts

Rob Attar and Steve Toomey present a balanced analysis, acknowledging that while the United States was on the lookout for conflict with Japan, the specific details of the Pearl Harbor attack were not within the purview of available intelligence at the time. This nuanced perspective challenges the notion that Pearl Harbor was an "inside job," suggesting instead that it was a meticulously planned military strike that capitalized on the broader geopolitical tensions of the era.

For those interested in an in-depth exploration of this topic, the full episode of "History's Greatest Conspiracy Theories" is available for subscription, offering a thorough examination of whether Pearl Harbor was indeed an inside job or a strategic surprise by Japanese forces.

Key Quotes

• "It's one of the most notorious surprise attacks in history." – Rob Attar [03:02]

• "The United States expected war in the Pacific any minute." – Steve Toomey [05:34]

• "The US had broken... the Japanese highest level diplomatic code... They were reading Japanese diplomatic messages in real time." – Steve Toomey [07:18]

• "Simply being told that something big was going to happen very soon, didn't say Pearl Harbor." – Steve Toomey [07:18]

Listen to the Full Episode

To dive deeper into this fascinating discussion, subscribe to History Extra and access the full episode of "History's Greatest Conspiracy Theories" wherever you listen to podcasts.

Transcript

[Podcast Host]

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[Podcast Host]

Today we want to give you a little taste of a new series that we're launching, the second season of History's Greatest Conspiracy Theories. In it, Rob Attar is joined by expert historians to explore some of the most pervasive historical conspiracy theories. From NASA faking the moon landing to the Knights Templar discovering America, they'll explore how these theories came about and whether any of them might actually be true. So here's a taster of the first episode in which Steve Toomey considers whether President Roosevelt might have known about the attack on Pearl harbor in advance of it happening. If you enjoy this clip, you can find the whole episode and subscribe to get the whole series by searching for history's greatest conspiracy theories wherever you listen to podcasts.

[Rob Attar]

On 7 December 1941, a day that would live in infamy, Japan attacked the US naval base at Pearl harbor, killing more than 2,400 people, sinking a number of ships and destroying dozens of aircraft. It's one of the most notorious surprise attacks in history. But how much of a surprise was it? Did US President Franklin Roosevelt know the attack was coming and even encourage it as a means of propelling the US into World War II? Welcome to episode one of season two of History's Greatest Conspiracy Theories from History Extra. I'm Rob Attar and to explore this backdoor to war conspiracy theory, I was joined by Steve Toomey, a Pulitzer Prize winning journalist and author of Countdown to Pearl Harbour. The 12 days to the Attack. Before we dig into the conspiracy theories, I wonder if you could briefly explain the events of 7th December 1941. The attack on Pearl Harbor.

[Steve Toomey]

The attack occurred at a time of incredibly tense relations between the United States and Japan. For months the two sides have been negotiating about how, my phrase, to get Japan to behave better. It was already at war in China. It had already extorted Indochina, or at least part of it from the French. There were negotiations going on in Washington about how to resolve things, the issues in the Pacific, amicably and peacefully. Those negotiations were ongoing in Washington in the first week of December 1941, unbeknownst, and we'll get to this, to the United States, Japan had already made the decision to go to war with the United States as well as with just about everyone else in the Pacific. And so the attack occurred during these negotiations, which added to the sense of betrayal and surprise that followed the attack itself. So this was not a case of the Pacific being a calm theater of war. While war raged in Europe, the Pacific was waiting to explode. Really?

[Rob Attar]

So you're talking about using words like surprise and betrayal. Now a lot of the conspiracy theories about Pearl harbor centre on this idea that actually the U.S. and its president knew the attack was coming and allowed it to happen anyway. So on that you mentioned, the Pacific was not a calm ocean at this time. To what extent did the US know or suspect that some kind of Japanese attack was imminent?

[Steve Toomey]

The United States expected war in the Pacific any minute. One of the difficulties in discussing the conspiracies surrounding Pearl harbor is the fact that many people think a surprise meant that it came out of nowhere. There was no reason for this. There was no context for this. And that's not true. Everyone in the United States government, from the President on down, expected war in the Pacific to break out at any minute. They had a lot of evidence of that. Everyone in the world knew that a large Japanese invasion force had set sail and was bound for the Southwest Pacific, toward Malaya and Singapore, Indochina, Indonesia, and most importantly, toward what was an American colony at that time, the Philippines. So the knowledge of that advancing force was widespread. It was literally in all the papers. So great or so concerned was the White House about where things were headed that it sent a message to Congress not to adjourn for the Christmas holidays because it might be needed to declare war. And this was all prior to the attack. So Franklin Roosevelt expected war. The American Navy, the American army expected war. What they didn't expect is where it actually also broke out.

[Rob Attar]

One of the things that's put forward quite often in support of the conspiracy theory is that various Japanese codes or forms of US Intelligence had given the US advanced knowledge of exactly where the attack was coming. What did they actually know from Japanese code intercepts and things like that? Did they have that kind of specifics?

[Steve Toomey]

The Japanese had many different codes, and the one that was broken was the Japanese highest level diplomatic code. Diplomatic code means the code that Tokyo used to converse with its embassies and consulates around the world. The US had broken that code in what really is an amazing feat of engineering and was reading Japanese diplomatic messages in real time. It wasn't a case of them reading them weeks later. They were reading them within 24 or 48 hours. Those codes which they were reading clearly indicated that something big was going to happen. Tokyo was telling its embassy in Washington where the negotiations were taking place, that big things are going to happen very soon unless we get a breakthrough here in terms of negotiations with the Americans. At no time did the diplomatic code disclose to the diplomats the targets of any attack or when it would occur, and there would be no reason for that. Tokyo had no reason to tell its diplomats the specifics of military operations. It simply was trying to alert them to what it was bent on, which was war in the Pacific. And when the US Read about these things that were automatically going to happen, as one message put it, that comported with what other intelligence showed them about the advance of Japanese fleets in the far eastern Pacific, southwest, Pacific, north. So simply being told that something big was going to happen very soon, didn't say Pearl Harbor. It comported with what seemed to be the plan of the Japanese, which was to expand their empire in their portion of the Pacific. The United States had not broken the most important code, at least in military terms, which was the Japanese naval code. How the Japanese military hierarchy in Tokyo communicated with ships at sea. The United States was not reading that code and wouldn't break it until after the war had started. Just as an aside, it broke that code in such in a way that it enabled the United States to surprise the Japanese at the Battle of Midway. But that was six months into the future and had not occurred. And I think people misunderstand when they hear that a code was broken that that means, aha. We knew what they were thinking and what they were going to do. It didn't. It was much more complex than that.

[Rob Attar]

So one of the, again, pieces of evidence put forward in support of the conspiracy theories, the idea that Pearl Harbour didn't seem in any way prepared for a Japanese attack. Had the US Authorities been warning bases such as Pearl harbor of potential attacks and encouraging them to be prepared?

[Steve Toomey]

Absolutely, it had. And as a result of what I just mentioned, the breakthroughs in the diplomatic code and other evidence Washington said, that.

[Podcast Host]

Was a clip from the first episode of season two of History's Greatest Conspiracy Theories. If you want to hear the full episode and subscribe to get the whole series, then just search for History's Greatest Conspiracy Theories wherever you get your podcasts. This is History's heroes. People with purpose, brave ideas, and the courage to stand alone, including a pioneering surgeon who rebuilt the shattered faces of soldiers in the First World War. You know, he would look at these men and he would say, don't worry, sonny, you'll have as good a face as any of us. When I'm done with you, you join me, Alex Von Tanzelman for History's Heroes. Subscribe to History's Heroes wherever you get your podcasts.