Israeli occupation of Palestine
Occupation of Palestine by Israel is the only ongoing (and even expanding) military occupation in the 21st century. The 50+ year long occupation is still a major cause of instability in the region and, due to the involvement of USA, in the world.
The occupation began in 1948 when Israel promptly breached the very U.N. resolution by which Israel was formed. Instead of protecting the current inhabitants within its partition as directed by the resolution, Israel began killing, terrorizing and expelling the indigenous people (mostly Arabs, both Muslims and Christians). Israel's pogroms of 1948 resulted in deaths, maiming and ethnic cleansing of more than 870,000 inhabitants of Palestine.
Israel then immediately began expanding into areas outside of its designated partition, waging wars on neighbors and steadily occupying more and more of Palestine and neighboring lands. Israel currently occupies more than 80% of the original Palestine (this is in addition to the Israel's occupation of parts of Jordan, Syria, Lebanon and Egypt).
Israel's occupation of Palestine has been repeatedly condemnded by the entire world (except for, occasionally, USA and its satellites such as Marshall Islands). Israel's rap sheet at the U.N. is longer than for any other offender in the U.N. history: Israel is currently in breach of at least 69 U.N. Security Council resolutions (many more resolutions were proposed but vetoed by the U.S.), as well as a number of the U.N. General Assembly resolutions. Most of these resolutions call for Israel to withdraw from the occupied areas, stop terrorizing the indigenous people and neighbors and cease violating the basic human rights of Palestinians.
However, thanks to the one-sided U.S. support of Israel and influence of Jewish interests over politicans and the media, Israel continues to openly and brazenly defy the international community. Israel is the only country in violation of numerous U.N. Security Council resolutions that has not been bombed for its disobeyance.