Creation of Israel, USA invading Vietnam, Korean Wars, Iraq invading Kuwait and Soviet invasion in Afghanistan.
Explanation:
These are the few notable major 20th century events that come to my mind first. With the creation of Israel in 14 May 1948 (a state still not recognized by the majority of the Muslim world) caused international controversy and led to many Palestinian rebellions and ultimately the 6 days war. Not to mention USA invading Vietnam and the Soviet Union invading Afghanistan which caused one million deaths and contributed to the downfall of the Soviet Union.
