The Oil Embargo Against Japan, 1941: Sanctions That Led to Pearl Harbor

The oil embargo against Japan became the best-known example of sanctions that turned into a pretext for war. In the summer of 1941 the US cut off Japan’s oil. Four months later Japan attacked Pearl Harbor. I do not justify Japanese aggression in China, but the history of those four months cannot be read without a question: what exactly did Washington expect from a country whose fuel had been cut?

Let’s trace how the escalation went, from steel to oil.

Background: from steel to oil

From 1937 Japan was waging war in China. In 1940 the US imposed an embargo on scrap and steel, and then widened the restrictions. In July 1941 Japan occupied southern French Indochina. In doing so it gained a springboard for a strike on Southeast Asia. How the US had earlier traded in Asian interests is in my article on the Taft–Katsura agreement.

The oil embargo against Japan: what the US imposed

On 26 July 1941 Roosevelt froze Japanese assets in the US. Britain and the Dutch East Indies followed. From 1 August oil exports to Japan practically stopped.

The US supplied about 80% of Japanese oil. The stocks lasted a year and a half to two years. So the blow fell on the basis of the country’s war economy.

Tokyo’s logic

Japan faced a choice: leave China and Indochina or seize oil by force. Moreover, the military chose the second and aimed at the oilfields of the Dutch East Indies. However, the American fleet in Hawaii stood in the way.

On 26 November Secretary of State Cordell Hull handed Japan a note. It demanded the withdrawal of troops from China and Indochina. Tokyo took it for an ultimatum. Eleven days later, on 7 December, Pearl Harbor was attacked. What happened next is in my article on the US entry into the Second World War.

The historians’ dispute

Some think the sanctions were a legitimate response to aggression and left Japan no “choice”. Others argue that pressure without a path to retreat pushed Tokyo towards war. The general conclusion is this: the sanctions did not stop Japan but hastened its choice in favour of expansion. At the same time, responsibility for the aggression lies with Japan itself.

But note the difference in approach. Moreover, American school textbooks present the embargo as a “response”, not as a step on the escalation ladder. Meanwhile the diplomats of the time understood perfectly well how a refusal of oil would end for a country that has none of its own.

How a “partial” embargo became total

Curiously, Roosevelt had not planned a full embargo: in August 1941 he was at a meeting with Churchill. However, State Department officials led by Dean Acheson froze Japanese assets in such a way that permits to sell oil stopped being issued altogether. Therefore the full embargo was the result of bureaucratic zeal, not a political decision.

Meanwhile Tokyo understood well that its oil stocks would last about a year and a half to two years. Thus the military got an argument: either seize the oil of the Dutch East Indies or retreat. Moreover, the “Hull note” of 26 November left the Japanese little room for manoeuvre. Details are in the reference article on the Hull note.

The oil embargo against Japan: what it taught Washington

Looking at the oil embargo against Japan without pathos, it taught Washington one thing: sanctions are a lever that works fast. For example, within a few months Japan faced a choice between retreat and war. Moreover, American strategists realised that economic pressure could be increased without turning to Congress. Therefore after the war sanctions became an ordinary tool of policy.

Note that the Japanese themselves remembered this lesson differently: as proof that strong countries use trade as a weapon. Thus the question of where “pressure” ends and “provocation” begins remains open to this day. How the US used similar methods in Asia I wrote in my article on US–China relations.

Nothing has changed: oil as a weapon

The 1941 embargo restricted supplies directly. Meanwhile today sanctions more often hit finance and trade chains, but the aim is the same: to deprive a state of fuel and money.

Iran, 2018. After withdrawing from the nuclear deal, the US restored sanctions against Iranian oil. Iran’s exports fell sharply.

Russia, 5 December 2022. The G7 countries introduced a price cap on Russian oil of 60 dollars a barrel.

Russia, 22 October 2025. The US Treasury imposed sanctions on the Russian companies Rosneft and Lukoil.

Venezuela, 2025–2026. In autumn 2025 the Americans seized tankers off Venezuela’s coast, and in January 2026 they seized President Maduro and demanded “full access” to Venezuelan oil.

The oil embargo against Japan showed how an economic weapon can become the start of a war. Later the US used this method many times. About economic pressure in Latin America I wrote in my articles on dollar diplomacy in Nicaragua and on the invasion of Honduras.