By Dan Williams
BEERSHEBA, Israel (Reuters) - Israel deployed a long-anticipated rocket shield outside the Gaza Strip on Sunday but cautioned Israelis under fire from the Hamas-run territory that they would not be completely protected.
The positioning of Iron Dome just north of Beersheba, a southern city twice hit by rockets during this month's flare-up of cross-border violence, was described by the military as an "acceleration" of the system's scheduled field evaluations.
Firing radar-guided missiles from a truck-sized launcher, Iron Dome is designed to track and blow up incoming threats in mid-air. Its development was stepped up after the 2006 Lebanon war and defense officials say it has aced several live trials.
But some experts have carped at what they see as needless delays and government protectionism in choosing Iron Dome -- produced by a state arms firm and partly underwritten by U.S. defense grants -- over ready alternatives available abroad.
"I do not want to create an illusion that the Iron Dome system, which we are deploying for the first time today, will provide a full or comprehensive response," Prime Minister Benjamin Netanyahu told his cabinet in Jerusalem.
"The real response to the missile threat is in the combination of offensive and deterrent measures with defensive measures, and with a firm stance by the government and public."
Netanyahu spoke shortly after Israel killed two members of Islamic Jihad, a Palestinian guerrilla group behind much of the recent rocket fire, in a Gaza air strike.
Hamas, the Islamist movement that controls Gaza and whose forces also took part in the fighting, said on Saturday shooting from the coastal enclave would cease if Israel held fire too.
Brigadier-General Doron Gavish, Israel's air defense chief, said whatever lull ensued was irrelevant to Iron Dome planning.
"We will carry out our evaluations regardless," he told reporters in the arid hillocks against the backdrop of Beersheba's bustling white apartment blocks.
"Regrettably, the way things look now, we will be required to provide our services for a long time hence."
He would not comment on the protective radius provided by the Beersheba battery. But its positioning suggested it could cover Sderot, an Israeli town on the Gaza border that has borne the brunt of almost a decade of mortar bomb and rocket attacks.
A second Iron Dome battery is due to be set up near the port of Ashkelon this week, Israeli media said. According to Gavish, each unit can be dismantled and ferried out "within hours," allowing for mobile responses over a large swathe of territory.
Industrial sources put the base price of each Iron Dome battery at about $50 million, with each interception costing $25,000.
That raised the prospect of the outgunned Palestinians taxing Israeli budgets with salvoes of the mostly inaccurate and homemade rockets that are sometimes worth just a few hundred dollars each. But rockets that hit Beersheba were factory-grade.
Gavish said the "missile versus missile" calculus was misplaced and "the real test is what damage is caused by a rocket that goes unintercepted."
Iron Dome's operators say it is designed to intercept only rockets that are about to hit residential areas, and ignore those on a harmless trajectory.
(Editing by Mark Heinrich)