According to Robert Dreyfuss, author of "Devil's Game: How the United States Helped Unleash Fundamentalist Islam":
"And beginning in 1967 through the late 1980s, Israel helped the Muslim Brotherhood establish itself in the occupied territories. It assisted Ahmed Yassin, the leader of the Brotherhood, in creating Hamas, betting that its Islamist character would weaken the PLO."
According to Charles Freeman, former US ambassador to Saudi Arabia, "Israel started Hamas. It was a project of Shin Bet [Isreali domestic intelligence agency], which had a feeling that they could use it to hem in the PLO."