Israel's religious affairs official in Gaza, Avner Cohen, later regretfully concluded that Hamas was created by Israel. https://en.wikipedia.org/wiki/Hamas

US Congressman Ron Paul says Israel helped create Hamas to destabilize Arafat who was very powerful at the time.

"But there is something bitterly ironic in Israel’s support for Fatah against Hamas—and it should be a lesson to governments everywhere that meddle in other states’ affairs. In the past, Israel supported Hamas against Fatah. Indeed, in the 1970s and 80s, Israel played a not insignificant role in encouraging Hamas’s emergence in the belief that such an Islamist group might help rupture support for the mass nationalist movement of Fatah. Twenty years later, Israel has switched sides, hoping that it can encourage Fatah to see off Hamas. It wants “moderate” Palestinians to take on the “extremist” Palestinians it helped create. Like America and Britain before it—both of whom have supported and armed Islamist movements in the Middle East in attempts to undermine secular nationalist parties—Israel is learning the hard way that it is one thing to let radical Islamists off the leash but quite another thing to rein them back in again. If you make monsters, you shouldn’t be surprised if they come back to bite you." https://www.filmsforaction.org/watch/ron-paul-israel-created-hamas/