The international cabal of hackers known as Anonymous is threatening a cyber-attack on the Israeli government’s computers in response to its interception of a Gaza-bound flotilla on Friday.

In a video that was uploaded to YouTube, the groups warns that if the siege on Gaza is maintained, it will have no choice but to go on the attack.

Open gallery view Israeli naval forces intercept two Gaza-bound vessels, Nov. 4, 2011. Credit: IDF Spokesperson's Unit

On Sunday, the websites of the IDF, Mossad and the Shin Bet security services were down. It is still not clear whether this was linked to threat of "Anonymous."

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In the video, the group accused the Israeli government of breaching international law and of piracy, because IDF naval commandos boarded the boats 35 nautical miles from the coast, in international waters.

“We do not tolerate this kind of repeated offensive behavior against unarmed civilians,” the group said in the video message.

“We along with 127 countries recognize Palestine as a state for the people of Palestine and such acts by you and your military are acts of war against a sovereign nation,” they added.

Anonymous said that if the siege continues and Israeli forces intercept additional flotillas, or if they conduct additional operations such as the commandeering of the Mavi Marmara, it will have no alternative but to launch repeated cyber-attacks on Israeli computer systems until the siege ends.

Anonymous has succeeded in the past in bringing about the temporary disabling of many websites, including credit card companies that refused to transfer donations to the WikiLeaks organization.

Several months ago, Anonymous announced that they have the code for Stuxnet, which was distributed on the internet. Security experts usually do not see them as a strategic threat, as they do programmers who are responsible for this type of malicious software.

Anonymous threatened to disable the Knesset website a few months ago, but even if hacking did occur then, the website continued to function and did not suffer any apparent damage.

"קראו כתבה זו בעברית: בעקבות המשט: ישראל על הכוונת של "אנונימוס