If Arabs were behind this, it would have been on the front page of the NYT

"Vandals spray-painted graffiti overnight Monday on the walls of Yad Vashem, Israel’s official Holocaust memorial, with messages attacking Zionism and blaming Zionists for the Holocaust. Nearly a dozen messages were scrawled around the Warsaw Ghetto Square monument and other parts of the campus. One said, “If Hitler hadn’t existed, the Zionists would have invented him,” and another said, “The Zionists wanted the Holocaust.” One message was signed “Global Haredi Judaism,” fueling suspicions that those behind the act were ultra-Orthodox Jewish extremists who reject the modern state of Israel." (thanks Houssam)