Among the countries listed, the one that was not created following World War I is likely the United States. The U.S. was established long before the war, gaining independence in 1776. Other countries that emerged after World War I, such as Czechoslovakia and Yugoslavia, were formed as a result of the geopolitical changes following the conflict.
The world doesn't 'need' war. War is the result of a breakdown in relations between countries.
World War.
Poland, Germany
9
Austria and Hungary
UN
Czechoslovakia, Yoguslavia,Jordan
Germany
The League of Nations
As a result of World War 2.
This was the first global conflict, with estimates ranging from 15 - 50 Million people killed. Many new independent countries were created as a result of this war.