A video released this week by the Anonymous hacker collective vowed to inflict an "Electronic Holocaust" on Israel.
The video shows a masked individual in a suit delivering a prepared statement, in which he announces April 7 as the date of a concerted attack on Israel's online servers. "As we did many times, we will take down your servers, government websites, Israeli military websites, and Israeli institutions," he said.
"We will erase you from cyberspace in our Electronic Holocaust."
The video includes images of Prime Minister Benjamin Netanyahu in a briefing room with the defense minister and military leaders, as well as distraught Palestinian children and bombed areas that appear to date from Operation Protective Edge.
Anonymous has specifically targeted Israel several times before. The group announced a campaign against Israel in November 2014, but no significant damage was reported.
While Israel is threatened with cyberattacks every few months, hackers often fail or cause minimal and temporary damage. In some cases lists of names and passwords of Israelis are released online, but these lists are sometimes outdated.
A cyberattack by Anonymous and other hackers hit Israel on April 7, 2014, but only a few sites were brought down temporarily.