Mr. Netanyahu was referring to Hamas, the Islamist movement that won the 2006 Palestinian legislative election, fought a brief civil war with Fatah, the secular-minded party of Palestinian President Mahmoud Abbas, the following year, and patched up differences with Mr. Abbas's party last month.
Hamas's crushing 2006 victory was largely due to Palestinian disaffection with Fatah. On top of failing to deliver a Palestinian state, Fatah's old guard was widely derided as corrupt by average Palestinians. In the years since, Hamas's often-thuggish rule in the Gaza Strip has eroded its popular support, though it remains one of the most powerful and cohesive forces in Palestinian society.
That reality, and the realization that a Palestinian house divided made a mockery of moves toward peace talks with Israel (since Abbas's government didn't speak for Gaza) led to the reconciliation of the two groups. Mr. Netanyahu is furious about this development.
There are, of course, good reasons for that. Hamas, unlike Fatah and the Palestinian Liberation Organization (PLO), hasn't formally recognized Israel's right to exist. Rocket fire has frequently poured out of a Gaza under Hamas control (though often fired by other groups, the Israeli argument has been that it's done with tacit Hamas approval), and the group is cozy with Iran and Syria.