REPORTING FROM JERUSALEM -- Last week, a hacker published credit card information belonging to about 20,000 Israelis on the Internet, along with the personal details of hundreds of thousands more.

Israeli credit card companies swiftly canceled the cards and pledged to reimburse customers for damages caused by fraudulent use.

The suspected hacker, identifying himself as OxOmar, claimed he was a Saudi teenager, based in Riyadh. But Israeli hackers embarked on a search for the credit card culprit and within hours announced he was actually based in Mexico, where he had moved from the United Arab Emirates.

The hacker's identity and location remain unclear. In subsequent messages, he said Israelis got the wrong guy.

Over the weekend, Deputy Foreign Minister Danny Ayalon talked tough on the issue, declaring cyber-attacks to be terrorism and saying that Israel would "retaliate forcefully." Then early Monday, Ayalon, a cyber-savvy politician and prolific user of social media platforms including Facebook and Twitter, found his website had been attacked and defiant comments left behind.

"We don't fear your empty words ... we are ready to be struck by your missiles and die a martyr's death for God," read one message written in Arabic.

Ayalon, for his part, said he would not back down to anyone, including those with computer skills.

"Cyberspace appears to be the new battlefield, and our opponents will not be able to defeat us on this plane either," he said.

Also Monday, a group of Israeli hackers said they got their hands on 1,000 credit cards used on Saudi shopping sites. The hackers threatened to "cause severe damage to the privacy of Saudi citizens" if attacks on Israel continued.

Some Arab media reports said Saudi banks were stepping up security after perceived Israeli threats. In other reports, banking officials dismissed concerns and said Saudi banks already spent a fortune on security and there was no need for extra measures.

Hebrew media reported that Israeli banking officials met with Homeland Defense Minister Matan Vilnai a few weeks ago and told him Israel's banking system, as well as other critical infrastructure like the electric company, trains and ports, were unprepared for cyber-terrorism. Israeli awareness is high but the bureaucracy is sluggish. However, the incident may expedite implementation of security measures.

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-- Batsheva Sobelman

Above: Screen shot of hackers' Arabic message on Deputy Foreign Minister Danny Ayalon's website Monday. Courtesy of Ayalon's office.