After World War I, Britain, Japan, and the United States were all expanding their navies, building larger and more advanced warships. Many members of the U.S. Congress were concerned about the enormous cost of military spending and were also worried about rising tensions in Asia. They urged President Harding to convene an international conference to address these issues.

The conference opened in Washington in November 1921. President Harding invited the world’s leading naval powers at the time, including Britain, Japan, France, and Italy. He also invited countries with significant interests in Asia, including China, Portugal, Belgium, and the Netherlands. The Soviet Union was not invited. At the opening of the conference, Harding politely asked the French delegation whether English could be used as the conference language. Out of respect for the host country, the French representatives agreed. In the past, nearly all international conferences had been held in Paris and conducted in French. This was the first time an international conference was held in Washington and conducted in English, symbolizing that the United States had become the leading power and had formally stepped onto the world stage.

Harding proposed that the major naval powers halt the construction of warships for the next ten years. He also suggested that Britain, Japan, and the United States scrap some of their existing warships and immediately reduce their naval strength. The delegates debated these proposals for three months. Japan ultimately secured the right to maintain a relatively larger fleet. Nevertheless, the agreements reached were very close to Harding’s original plan.

The naval treaty concluded at the 1921 Washington Conference was the first agreement in which the world’s major powers jointly agreed to limit military strength. Most people regarded it as a good treaty.

In the summer of 1923, Harding traveled to Alaska and several western states on an inspection tour. On the return trip, he fell ill in San Francisco and died of a heart attack. When Vice President Calvin Coolidge received the news of Harding’s death, he was in Vermont in the northeastern United States. Coolidge’s father was a local justice of the peace and administered the oath of office to his son. Coolidge thus became the 30th president of the United States.