Several western Allied governments placed embargoes on Japan in response to its actions in China. I assume, though I'm not certain, that it contributed to Japan's decision to declare war against the United States and the British Empire. I can understand why allied governments had a dim view of Japan's actions, but I don't understand why they decided to get involved.

Wasn't their (except technically for the USA) war with Germany and Italy such a monumental undertaking that being at war with Japan at the same time too risky a move to make? Why didn't they decide to ignore the Japanese government for a while, until Germany and Italy were largely or totally defeated?

  • 4
    This should probably be asked on History.SE. Politics is more for questions about current systems. Dec 9, 2015 at 9:43
  • @PointlessSpike I thought that question about historical politics are preferred on the politics site rather than the history site. Dec 9, 2015 at 9:54
  • 3
    I think it's more the history of current political systems that are preferred here. You're not asking for an explanation of a current system using history, you're asking about events in history. To put it another way, you're primarily advancing you're understanding of history, not current politics. Dec 9, 2015 at 10:02
  • Downvote because the marked answer is false.
    – FluidCode
    Jun 24, 2021 at 12:54
  • Somewhat sad to to see such an old post closed by hammer now. Since migration isn't optoinal anymore: can you think of an actually similar angle, fit for HistorySE? Jun 25, 2021 at 21:36

4 Answers 4


Because by 1940, the Japanese invasion of the Dutch East Indies became imminent.
These colonies were rich in oil, so such an invasion would ruin the energy stability of Europe and the U.S.

The Japanese invasion of China started in 1937 and cost about 30 million lives; it was associated with use of chemical weapons, forced labor camps, medical experiments on prisoners, and many other acts. However, these actions did not get a response:

On 12 September 1937, the Chinese representative, Wellington Koo, appealed to the League of Nations for international intervention. Western countries were sympathetic to the Chinese in their struggle… However, the League was unable to provide any practical measures; on 4 October, it turned the case over to the Nine Power Treaty Conference.Wikipedia

For example, in U.S. the policy of Non-interventionism was very popular. In a 1940 speech, Roosevelt argued,

"Some, indeed, still hold to the now somewhat obvious delusion that we … can safely permit the United States to become a lone island … in a world dominated by the philosophy of force."

It is important to know that Japan not only invaded China; they also invaded and occupied Indo-China, Malaya, and Philippines, gradually moving South. Japanese troop build ups in Hainan, Taiwan, and Haiphong were noted.

Japanese strategists also had confirmed plans to take control of Dutch East Indies. And they actually did it January 1942.

In September 1940 Japan was assured that Germany and Italy would respect Japanese interests in the Asia-Pacific region by signing the Tripartite Pact.

On 24 July 1941 Roosevelt requested that Japan withdraw all its forces from Indochina. Two days later the U.S. and the U.K. stopped selling oil, iron ore, and steel to Japan.

As we know, instead of withdrawal, the Japanese government began planning military actions against the Allies.

Summary. Opposing Japan was not very popular in the U.S. and Europe, but the emerging threat of losing control over oil/iron resources plus a chain of escalating events embroiled the Western Allies in opposing Japan.

  • 2
    The Japanese invasion of the Philippines started only after Pearl Harbour: en.wikipedia.org/wiki/Japanese_occupation_of_the_Philippines The threat on that American colony was part of the US concern about Japanese expansionnism, but the invasion itself should not be listed among the casues of the blocade by US and UK.
    – Evargalo
    Oct 25, 2017 at 7:19
  • Malaya & Philippines at least were post Pearl Harbour. Mar 18, 2020 at 10:25
  • This answer is swapping the cause and the effect. Japan invaded the Dutch East Indies, the Philippines and the colonies in IndoChina because of the embargoes.
    – FluidCode
    Jun 21, 2021 at 16:04

To add to @bytebuster's excellent answer, Japan was threatening (with addition of Greater East Asia Co-Prosperity Sphere) to turn into a geopolitical powerhouse, spanning a large geographic area and commanding lots of natural resources AND human ones. It's never in the interest of established geopolitical powers (in this case, Western allies) to allow such to come into existence - same reason USA opposed Russian/Soviet domination of Western Europe, or earlier, Germany's domination of Eurasia.

Once you are a large geopolitical power, you possess enough resources to make it very hard to knock you off your perch - which means the best, or even only, strategy, is to check an emergent power before it expands sufficiently.

  • How much of an industrial base did Japan have compared to established world powers? Dec 7, 2015 at 20:59
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    @AndrewGrimm: Enough to produce a navy that could soon have become equal to the pacific flotilla of the US within years. Dec 8, 2015 at 13:26
  • Japan NEVER had the resources to beat the US long term. eg Yamamoto was aware of this. The best they could have hoped for was to have carved out enough territory and been enough of a nuisance that a negotiated settlement would have been acceptabvly less expensive to the US than what instead happened. Similar to Hitler's position with UK where a negotiated peace was a very real prospect until the old warmonger Churchill stepped in to set in motion events that eventually saved the day. Thank God for Churchill! :-) Mar 18, 2020 at 10:28

Several western Allied governments placed embargoes on Japan in response to its actions in China. I assume, though I'm not certain, that it contributed to Japan's decision to declare war against the United States and the British Empire.

Below are sources from a US State Department page and a page from an Encyclopedia of American Foreign Policy

(Edit: Adding a list of embargo contents and dates given by the Independent)

The describe describe and date the series of actions and counter actions taken by the US and Japan over the period 1937-1941.

To summarize:

  • Indeed, before 1941 the US, Britain, etc., did not want to get over involved in China. But since the US took a dim view, China was included in the lend lease program, and the US revoked a trade agreement with Japan, but without actually yet imposing an embargo.

  • In 1940/41, Japan signed a non-agression pact with the USSR, allowing a pivot to SE Asia, and also signed the Tri-Partite pact with Germany and Italy for mutual support. The US embargoed aviation fuel, scrap iron, metal, and military hardware.

  • Japan moved troops into Indo-China on July 24, 1941, with the permission of by then German controlled Vichy France. On July 26, 1941, the US placed an embargo on all fuel and froze all Japanese assets.

So it was a series of "raising" the stakes - and neither side backing down.

Japan, China, the United States and the Road to Pearl Harbor, 1937-41

Between 1937 and 1941, escalating conflict between China and Japan influenced U.S. relations with both nations, and ultimately contributed to pushing the United States toward full-scale war with Japan and Germany.

At the outset, U.S. officials viewed developments in China with ambivalence. On the one hand, they opposed Japanese incursions into northeast China and the rise of Japanese militarism in the area, in part because of their sense of a longstanding friendship with China. On the other hand, most U.S. officials believed that it had no vital interests in China worth going to war over with Japan. Moreover, the domestic conflict between Chinese Nationalists and Communists left U.S. policymakers uncertain of success in aiding such an internally divided nation. As a result, few U.S. officials recommended taking a strong stance prior to 1937, and so the United States did little to help China for fear of provoking Japan.

U.S. likelihood of providing aid to China increased after July 7, 1937, when Chinese and Japanese forces clashed on the Marco Polo Bridge near Beijing, throwing the two nations into a full-scale war. As the United States watched Japanese forces sweep down the coast and then into the capital of Nanjing, popular opinion swung firmly in favor of the Chinese. Tensions with Japan rose when the Japanese Army bombed the U.S.S. Panay as it evacuated American citizens from Nanjing, killing three. The U.S. Government, however, continued to avoid conflict and accepted an apology and indemnity from the Japanese. An uneasy truce held between the two nations into 1940.

In 1940 and 1941, President Franklin D. Roosevelt formalized U.S. aid to China. The U.S. Government extended credits to the Chinese Government for the purchase of war supplies, as it slowly began to tighten restrictions on Japan. The United States was the main supplier of the oil, steel, iron, and other commodities needed by the Japanese military as it became bogged down by Chinese resistance but, in January, 1940, Japan abrogated the existing treaty of commerce with the United States. Although this did not lead to an immediate embargo, it meant that the Roosevelt Administration could now restrict the flow of military supplies into Japan and use this as leverage to force Japan to halt its aggression in China. After January 1940, the United States combined a strategy of increasing aid to China through larger credits and the Lend-Lease program with a gradual move towards an embargo on the trade of all militarily useful items with Japan.

The Japanese Government made several decisions during these two years that exacerbated the situation. Unable or unwilling to control the military, Japan's political leaders sought greater security by establishing the "Greater East Asia Co-Prosperity Sphere" in August, 1940. In so doing they announced Japan's intention to drive the Western imperialist nations from Asia. However, this Japanese-led project aimed to enhance Japan's economic and material wealth so that it would not be dependent upon supplies from the West, and not to "liberate" the long-subject peoples of Asia. In fact, Japan would have to launch a campaign of military conquest and rule, and did not intend to pull out of China.

At the same time, several pacts with Western nations only made Japan appear more of a threat to the United States. First, Japan signed the Tripartite Pact with Germany and Italy on September 27, 1940 and thereby linked the conflicts in Europe and Asia. This made China a potential ally in the global fight against fascism. Then in mid-1941, Japan signed a Neutrality Pact with the Soviet Union, making it clear that Japan's military would be moving into Southeast Asia, where the United States had greater interests. A third agreement with Vichy France enabled Japanese forces to move into Indochina and begin their Southern Advance. The United States responded to this growing threat by temporarily halting negotiations with Japanese diplomats, instituting a full embargo on exports to Japan, freezing Japanese assets in U.S. banks, and sending supplies into China along the Burma Road.

Although negotiations restarted after the United States increasingly enforced an embargo against Japan, they made little headway. Diplomats in Washington came close to agreements on a couple of occasions, but pro-Chinese sentiments in the United States made it difficult to reach any resolution that would not involve a Japanese withdrawal from China, and such a condition was unacceptable to Japan's military leaders. Faced with serious shortages as a result of the embargo, unable to retreat, and convinced that the U.S. officials opposed further negotiations, Japan's leaders came to the conclusion that they had to act swiftly. For their part, U.S. leaders had not given up on a negotiated settlement, and also doubted that Japan had the military strength to attack the U.S. territory. Therefore they were stunned when the unthinkable happened and Japanese planes bombed the U.S. fleet at Pearl Harbor on December 7, 1941. The following day, the United States declared war on Japan, and it soon entered into a military alliance with China. When Germany stood by its ally and declared war on the United States, the Roosevelt Administration faced war in both Europe and Asia.


Embargoes and Sanctions - World war ii

In July 1940, a cabinet change in Japan signaled a more aggressive Japanese policy in South-east Asia. With that, the United States imposed an embargo on aviation gasoline and high-grade scrap iron to Japan. This embargo affected only a fraction of exports to Japan, and the U.S. government went to some lengths to justify the embargo on the grounds of American domestic needs rather than any displeasure with Japan. Still, the embargo signaled the Japanese that the United States would oppose any moves against Southeast Asia.

Instead of backing down, Japan accelerated its search for more secure sources of vital raw materials. It extorted concessions from the Dutch East Indies, coerced Vichy France into allowing Japanese occupation of northern Indochina, and began negotiations for an alliance with Germany and Italy. The United States responded with a complete embargo on scrap iron, but this was followed the very next day by the formal announcement of the Axis pact. The United States continued to expand its embargo, extending it to tools, iron, steel, copper, bronze, and many other critical metals. When the United States intercepted Japanese messages detailing plans for further expansion in Southeast Asia and reports arrived that Japanese transports were moving on southern Indochina, Roosevelt decided on a last-ditch gamble to stop Japanese expansion. He issued an order freezing all Japanese assets in the United States. Only a special license from the U.S. government could release Japanese assets to pay for American exports, including, most critically, oil. When the British and Dutch joined the oil embargo, it cut off the vital Southeast Asian sources of raw materials as well. With only a two-year supply of petroleum, Japan either had to give up the war in China or secure its own sources of supply. Japan first tried diplomacy, but negotiations with the United States failed, and Japan declared war. During World War II, the United States used the 1917 Trading with the Enemy Act to impose a complete embargo on the Axis powers.

NOTE: The following resource fails to interleave the history of Japanese actions with the embargoes, including the events of July 24, 1941, when Japan occupied French Indo-China

"How U.S. Economic Warfare Provoked Japan’s Attack on Pearl Harbor", The Independent Institute

Accordingly, the Roosevelt administration, while curtly dismissing Japanese diplomatic overtures to harmonize relations, imposed a series of increasingly stringent economic sanctions on Japan. In 1939 the United States terminated the 1911 commercial treaty with Japan. “On July 2, 1940, Roosevelt signed the Export Control Act, authorizing the President to license or prohibit the export of essential defense materials.” Under this authority, “[o]n July 31, exports of aviation motor fuels and lubricants and No. 1 heavy melting iron and steel scrap were restricted.” Next, in a move aimed at Japan, Roosevelt slapped an embargo, effective October 16, “on all exports of scrap iron and steel to destinations other than Britain and the nations of the Western Hemisphere.” Finally, on July 26, 1941, Roosevelt “froze Japanese assets in the United States, thus bringing commercial relations between the nations to an effective end. One week later Roosevelt embargoed the export of such grades of oil as still were in commercial flow to Japan.”[2] The British and the Dutch followed suit, embargoing exports to Japan from their colonies in southeast Asia.

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    Noting US actions is correct, but also the British Empire took actions against Japan and that was an embargo.
    – FluidCode
    Jun 21, 2021 at 16:25
  • My wording was misleading - I most certainly meant to include embargo. But instead of fixing that, I found better sources and based on that wrote a more accurate answer. Jun 22, 2021 at 1:52

The discussions to place Japan under embargo started after the Nanjing Massacre which happened in 1937. The agreement to start the embargo was reached before the outbreak of the war

Furthermore, the occupation of French Indochina was a consequence of the embargo, which already began because it was officially declared. Therefore it is not a reason for the embargo.

  • There were various stages of embargo (see my answer above). Japan occupied French Indo-China on July 24, 1941. It was only after that that the US embargoed all fuel, beginning July 26, 1941. I added a resource to my above answer which gives detailed dates. The resource itself leans anti-US. so I trust it not to make the embargo dates later than they really were. However, the resource omits any account of Japanese actions. When those actions are collated into the timeline, we are better able to surmise US diplomatic strategy and goals - which the OP asked for. Jun 25, 2021 at 23:47
  • @CraigHicks It seems you are relying on the omission of earlies actions taken by the British Empire to give a false impression about what is the cause and what is the effect.
    – FluidCode
    Jun 26, 2021 at 10:37

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