Three Israeli government websites - involving army and intelligence - were down on Sunday a few days after a threat from a hacker group.
Although it cannot be confirmed, it is believed that Anonymous is responsible.
The sites went down after the hacker group appeared to issue threats to the Jewish state over its interception of a Gaza-bound flotilla.
The public (external) sites for the Israel Defense Forces (IDF), Shin Bet domestic intelligence agency and the Mossad spy agency all went down over the weekend.
"We can confirm that the website has been down for several hours and an investigation is ongoing," a Shin Bet spokesperson told AFP.
It was also verified by the Israeli army that its site had gone offline for several hours, with no explanation as to why.
"Initial investigations conducted by Tehila, the Internet company, indicate problems with the website servers," said an IDF spokesperson.
The website outages occurred two days after a video from the hacker collective Anonymous was posted on YouTube. In the video Anonymous threatens the Israeli government for intercepting two Gaza-bound ships, the group mentions retaliation and it looks like it may have delivered.
The vessels carrying 27 activists, crew and journalists were stopped in international waters before they could get past Israel’s naval blockade.
The video is titled "An open letter from Anonymous to the Government of Israel," and it accuses the Jewish state of "piracy on the high seas."
"If you continue blocking humanitarian vessels to Gaza or repeat the dreadful actions of May 31st, 2010 against any Gaza Freedom Flotillas then you will leave us no choice but to strike back," the video warns.
Because of the way Anonymous operates from the shadows, it was not possible to immediately confirm if the video was actually posted by the hacker group. Recently they’ve kept busy with their involvement in exposing details of individuals who visited child porn sites.
It was also not clear if the group was directly responsible for the downed websites over the weekend, and Israeli officials did not comment on the issue.
The websites appear to be back up now after reportedly being down for most of the weekend. It will be interesting to see if there is a response and/or an escalation from either side involved.