Which led Japan's Tokugawa shoguns to adopt a policy of isolation?

Tokugawa´s seclusion edicts issued in the 1600s aimed to interrupt the rapid expansion of Christianity in Japan. Catholic converts were increasing in number, challenging Buddhism precepts and also acquiring political and economical power in important port cities as Nagasaki. Two edicts closed the borders for foreigners and prevented Japanese people from leaving the country.

By restricting the daimyōs' ability to trade with foreign ships coming to Japan or pursue trade opportunities overseas, the Tokugawa bakufu could ensure none would become powerful enough to challenge the bakufu's supremacy.

Explanation:

although world war i began in 1914, the united states did not join the war until 1917. the additional firepower, resources, and soldiers of the u.s. to tip the balance of the war in favor of the allies. remaining neutral. when war broke out in 1914, the united states had a policy of neutrality.