Ammon News - HERZLIYA, Israel | (Reuters) - The United States would notify Israel hours in advance of an attack on Syria, an Israeli official said on Sunday.

While formally on the sidelines of the Syrian crisis, Israel fears coming under reprisals from its northern foe should the United States launch strikes to punish Damascus for alleged use of chemical weaponry.

Asked how much advance notice Israel would get from its U.S. ally about such attacks, an Israeli official briefed on contacts with Washington told Reuters: "Hours."

But a senior strategist for the Defense Ministry said separately Israel was, like the rest of the world, in the dark at present.

"Will the United States attack? Will it not attack? What will the consequences be? All of these things are unknowns," Amos Gilad said in a speech at the International Institute for Counter-Terrorism near Tel Aviv.

President Barack Obama has run into formidable U.S. domestic opposition to military action. Wary of appearing to meddle in American affairs, most Israeli officials have not publicly commented on the debate.

Israel plans to deploy anti-missile systems and troop reinforcements on its Syrian and Lebanese fronts if Obama green-lights strikes against Syria.

MISSILE INTERCEPTORS

Reuters television filmed what looked like an Iron Dome missile interceptor battery being positioned on the outskirts of Jerusalem on Sunday. "We don't comment on our aerial defenses," a military spokeswoman said.

An Israeli military magazine, Bamahane, said a month ago there were six such batteries deployed around the country and occasionally rotated geographically.

Obama has asked Congress to approve strikes against Syrian President Bashar al-Assad's government in response to a chemical weapons attack on August 21 that killed more than 1,400 Syrians.

Next week in Washington, hundreds of activists of the influential pro-Israel American Israel Public Affairs Committee will lobby Congress for military action in Syria.

Some Israeli officials have privately voiced concern U.S. failure to attack Syria would embolden Iran, an ally of Damascus, in its defiance of international calls to curb a nuclear program which the West fears is aimed at developing nuclear arms - a charge Tehran denies.

Gilad disagreed with those assessments, however, saying in his speech: "Whether or not this is popular, I don't recommend drawing conclusions about Iran from Syria."

Gilad noted Obama's declarations that he would not allow Iran to get the bomb, backed by U.S.-led diplomatic and economic pressure as well as military mobilization in the Gulf.

"I recommend attributing a high level of credibility to his statements (on Iran)," Gilad said.