Hacktivist collective Anonumous threatened to launch a cyber attack on Israeli websites on Sunday, April 7, the eve of Holocaust Memorial Day.The attack, dubbed "OpIsrael," sets to "disrupt and erase Israel from cyberspace."In a press release posted on Twitter, the group cites the reasons for their planned attack."To the government of Israel: You have NOT stopped your endless human right violations. You have NOT stopped illegal settlements. You have NOT respected the ceasefire. You have shown that you do NOT respect international law," they accused.In a YouTube video, Anonymous makes further accusations, saying Israel has threatened to shut down the internet in Gaza. "When the government of Israel publicly threatened to sever all internet and other telecommunications in and outside of Gaza, they crossed a line in the sand," a disembodied Guy Fawkes mask says.Anonymous warned Israel not to shut down the internet in Gaza and to "cease and desist from your terror upon the innocent people of Palestine or you will know the full and unbridled wrath of Anonymous." In an e-mail sent to Knesset employees Thursday, Deputy Information Security Officer Ofir Cohen explained that on Sunday, government websites are expected to face distributed denial of service (DDoS) attacks and attempts at vandalism."The estimations are that [the cyber-attacks] will reach an unusual level that we have never seen before," Cohen wrote, adding that the E-government, the government information security body, and the Knesset's internet service provider (ISP) are working to block the attack.The Knesset is bolstering its usual cyber security measures, which include a firewall meant to deter DDoS attacks. The Information Security Department of the Knesset is updating online security as well as sharing information with other government offices in preparation for the expected attack.Anonymous launched a wide-scale attack in November of last year during Operation Pillar of Defense on hundreds of Israeli websites The attacks ranged from prominent targets such as the Foreign Ministry to smaller Israeli businesses. During that series of attacks most of the sites were simply unavailable but others displayed pro-Palestinian images and messages.