The UN Charter says that countries are henceforth not to acquire territory by force.

That article is the whole basis for the US and NATO and European Union condemnation of Russia’s invasion and occupation of part of Ukraine.

Israel’s seizure of the Palestinian West Bank and the Gaza Strip in 1967 was therefore illegal. Its annexation of Palestinian East Jerusalem was illegal, and was branded such by the United Nations Security Council.

The laws of military occupation envision a time-limited occupation during the shooting war. Since the Hague Regulations of 1907 occupiers have been forbidden to alter the lifeways of the people who are occupied. They may not expel them arbitrarily from their homes. And they may not send their own citizens into the occupied territory to settle it. These actions were proscribed in the Geneva Convention of 1949 and in the Rome Statute.

These actions were made illegal in international law to forestall a repetition of Nazi Germany’s policies in Poland, where Berlin made a concerted attempt to remove Poles and replace them with Germans so as to “aryanize” the territory and make it part of Germany.

Israel has violated all of these provisions of international law, in a concerted and deliberate manner for over half a century. It has been actively and consistently aided in doing so by the United States, France, Britain, Germany, Canada and other industrialized democracies, under the cover of a phony “peace process” supposedly working toward a “two-state solution,” which has never amounted to more than weasel words and ways of avoiding any confrontation with Israel over its lawlessness. An undertone of white nationalist racism toward the brown Palestinians tinged this outrageous insouciance toward international law, this profound betrayal of post-war ideals.

Source: Tribalism versus International Law in the Israeli-Palestinian Conflict