On an international law level, the main problem with Israel is that it fought several independence wars after the Right of Conquest was outlawed by the UN Charter.

Just compare what happened to Poland - literally moved dozens of miles to the West, in an agreement signed in August 1945.

Then in October 1945 the UN Charter (art. 2, par. 4) removed the Right of Conquest.

This meant that in 1949 Israel could only get armistice borders from the enemy Arab states. The border with Egypt was only recognised in 1973, and the one with Jordan only in 1994, but since Jordan had already recognised the Palestinian state by then, and this still has to agree any border with Israel, the situation remains very vague both in Gaza and in the West Bank.

I wonder how many people know that most of the borders of Israel are NOT protected by the UN Charter.