Except we didn’t. As you seem to need to be hand-held through everything, here are the basics:
- As Israel does not see itself as an occupying power Israel does not feel the need to act as an occupying power as set by the Geneva Conventions.
- The UN argues that Israel is an occupying power.
- (My guess) The UN Security Council is responsible for enforcing such things and creating resolutions regarding Israel and the occupying power status.
- The US, as a permanent member of the UN Security Council with veto rights, throws a hissy fit whenever Israel is even remotely criticised and hence nothing gets done.