How did japan develop a trade surplus in the decades after world war ii?

Japan had to spend very little on defense because the U.S. was providing protection for them at the time. Japan had a skilled workforce and experience in industrialization, and that allowed the country to quickly rebuild after the war. The exports of Japan were of very high quality, and the government put high tariffs on imports, stimulating an export industry.

Ataxation measure enacted to raise revenues for a standing british army in america