Hamas leader Yahya Sinwar said: “What’s the problem if hundreds of thousands storm this fence which is not a border of a state? What’s the problem with that?“
https://www.independent.co.uk/news/world/middle-east/gaza-protests-latest-israel-shot-dead-border-march-gunfire-palestine-sinwar-hamas-a8347366.html

It has been the border of the state of Israel since its inception.
Hamas denies Israel the right to exist.