Why was the balkan region referred to as the powder of keg of europe prior to world war i?

In shifting to a defense policy based upon the concept of "flexible response," president kennedy was indicating that he had grave doubts about thevalue of which previous defense policy? a massive retaliationb collective securityc containmentd air power

Prior to the presence of europeans on the continent, the slave trade in africa a) did not exist in any form. b) was limited to internal trade only. c) included the trans-saharan and indian ocean slave trade. d) was rarely needed due to the lack of an agricultural economy.

Where were the trials to review evidence in cases against high-ranking nazi officials accused of war crimes held?