The rare sight of Israeli and Jordanian aircraft flying in tandem appears to indicate a new, stepped-up level of military and defense cooperation.

"We have credible information that the agent used in the attack was mustard," a senior US official told the 'Wall Street Journal'.

"Improvement of Hebrew among Arab students will result in their ability to more easily integrate into the Israeli workforce, and economy and society at large," he added.

The Arleigh-Burke class destroyer has been deployed to help defend Israel from the threat of ballistic missiles from Iran, Syria and Iraq, US ambassador says.

Several threatening letters have arrived at the embassy, which is in Tel Aviv, over the past week, numerous Israeli media outlets reported.

Nasrallah, who gave the speech from his hiding place, praised "the heroes of the resistance who fought to their last drop of blood in July 2006."

Muhammed Allan, who has been on hunger strike for 59 days, has been put on a respirator according to hospital spokesperson.

Open democracies like the US, or Israel for that matter, have weak underbellies, are far more vulnerable to cyber attacks and are less ready to hack back too hard.