ELI5: I get the war on drugs in the USA, but how did marijuana become illegal in almost every other country in the world as well?

Short Answer - In a panic that gripped America, marijuana was banned. The U.S. told other countries they had to do the same. Many countries said it was a dumb idea, and refused to do it. Still the majority of the countries kept the decision under the influence of USA and because there was not any other significant study proving otherwise. Although in recent years many countries have allowed the use of Marijuana legally.

Details - ....
https://www.reddit.com/r/explainlikeimfive/comments/6dtq8x/eli5_i_get_the_war_on_drugs_in_the_usa_but_how/