How the US and Japan Went From Enemies to Allies After WWII

During World War II, the United States and Japan fought as bitter enemies. Yet during the Cold War and beyond, Japan arguably became America’s closest and most reliable ally in the Asia Pacific region. How did they make such a successful transition from enemies to allies?

It’s difficult to imagine such a profound turnaround. In December 1941, Japan’s surprise bombing of Pearl Harbor shocked America, drawing it formally into the conflict. Nearly four years later, the U.S. dropped two devastating atomic bombs on the Japanese cities of Hiroshima and Nagasaki, effectively ending the war. Afterward, it subjected Japan to a seven-year-long postwar occupation that dismantled the vanquished nation’s military and radically changed its political structure.

But after the war, America’s goal wasn’t just to establish peace and rebuild Japan. Facing a new world order, the burgeoning superpower sought to turn the small but historically powerful Pacific island nation into its Asian bulwark against the spread of communism. To do that, American occupiers took important lessons from the aftermath of World War I. They leveraged the Japanese population’s desperate economic state and disillusionment with its government and military to sow the seeds of democracy and rewrite the constitution. And through it all, they deployed several thousand Japanese American military intelligence linguists, who proved as critical to the postwar transition as they had secretly been during the war itself.

General Douglas MacArthur, the Allied powers’ supreme commander overseeing Japan’s postwar transition, took seriously lessons learned from post-World War I treaties. Instead of humiliating the defeated country and demanding massive reparation payments like those that had dragged down Germany’s economy, America set the stage for a more positive relationship with its treatment of a defeated Japan—especially its Emperor.

Fearing a massive famine in the devastated country, Americans airlifted in food to stave off the humanitarian crisis and possible subsequent unrest. Instead of trying the hawkish Emperor Hirohito for war crimes, the U.S. strategically allowed him to remain on his throne as a figurehead, establishing a narrative that he had been betrayed during the war by more militaristic forces. By letting the nation’s leader save face, President Harry Truman’s administration reasoned, he could more effectively encourage citizens to cooperate with the occupation and the difficult task ahead: a transition from an ultranationalist imperial state to a democratic one.

Sidney Mashbir, a colonel in the Allied Translator and Interpreter Section (ATIS) of U.S. military intelligence, encouraged MacArthur to avoid embarrassing the emperor by forcing him to read a prepared script, according to John Toland, author of The Rising Sun: The Decline and Fall of the Japanese Empire. The emperor’s voice—never before heard by Japanese citizens—was high-pitched and formal, and his carefully crafted prerecorded message, delivered on August 15, 1945, never used the word “surrender.” Instead, he implied that Japan was choosing peace instead of continuing a now atomic-level war—one that might obliterate Japan and lead to human “extinction.”

After decades of feeding Japanese people the virtues of imperialism and expansionism, the emperor stressed in his speech the need for humility and stoicism: "The hardships and sufferings to which our nation is to be subjected hereafter will be certainly great." Japanese citizens, he stated, must “endure the unendurable and bear the unbearable.” The formal surrender took place on September 2, 1945, aboard the USS Missouri in Tokyo Bay, administered by General MacArthur.

In midwifing Japan’s transition to a democratic society, the U.S. understood the importance of public buy-in. The document outlining America’s post-surrender policy for Japan emphasized that while “the United States desires that this government should conform as closely as may be to principles of democratic self-government…it is not the responsibility of the Allied Powers to impose upon Japan any form of government not supported by the freely expressed will of the people.”

To be sure, the military government under MacArthur had broad power and control while overseeing Japan’s economic, sociopolitical and cultural transition. Yet, to help Japanese people avoid "the loss of self-respect and self-confidence," according to the general's official staff reports, occupation teams served as overlay to the existing civil structure, encouraging local officials and citizens to take initiative as much as possible in implementing prescribed reforms. U.S. forces still supervised the process, and there was still plenty of mutual animosity, but their largely civil and respectful treatment of Japanese citizens would build trust and serve the long-term objectives.

When fighting the Japanese during World War II, America deployed a secret weapon: first-generation Japanese Americans (Nisei) who served as linguists of the Military Intelligence Service in the Pacific theater. Born to Japanese immigrant parents, some Nisei spoke Japanese—especially the ones called Kibei, whose parents had sent them back to Japan to be educated before the war. Anticipating possible conflict with Japan, the U.S. recruited and trained Nisei to gather intelligence before Pearl Harbor; but after the attack and the subsequent incarceration of Americans of Japanese descent, they served the nation while subject to heightened discrimination and suspicion.

During the war, Nisei linguists monitored communications, translated maps and documents and helped interrogate enemy prisoners. In 1944, General Charles Willoughby, MacArthur’s intelligence chief, once boasted that “a single ATIS language expert was worth one infantry battalion.” He estimated that Japanese American linguists helped shorten the war by two years.

The Nisei also played a significant role during the Allied occupation and reconstruction of Japan. More than 5,000 served during the occupation, many as part of the military government teams assigned to each prefecture. The Kibei proved particularly important because they had a more intimate understanding of the country’s historical, sociopolitical, cultural, religious, economic, educational and practical norms.

During the critical first few months of the occupation, the Nisei and Kibei labored behind the scenes on numerous, often complex objectives. They worked to return American and Allied prisoners of war and to bring Japanese soldiers and civilians living abroad home to Japan. They aided in the release of political prisoners, participated in the search for war criminals and in gathering evidence for their prosecution. They monitored the populace for any signs of resistance that may thwart the nation’s democratic shift. On the financial front, they helped dismantle and destroy Japan’s war-related industries, and made efforts to break up financial conglomerates, wartime black markets and organized crime.

Perhaps most significantly, the Nisei/Kibei also assisted in the writing of Japan’s new constitution. Containing some 103 Articles, it went into effect on May 3, 1947. Its sweeping provisions encompassed land reform, women’s suffrage, the establishment of free speech, assembly and religion, the institution of labor unions and establishment of U.S. style educational systems.

Of key importance in the new constitution was Article 9, in which Japan renounced military aggression. It stated, **“**Aspiring sincerely to an international peace based on justice and order, the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes. In order to accomplish [this] aim…land, sea, and air forces, as well as other war potential, will never be maintained. The right of belligerency of the state will not be recognized.”

As geopolitics have shifted in the Pacific and elsewhere over the decades, this article has been the subject of debate in Japan and nations abroad. But the constitution has never been amended.