The Israeli military deployed the first mobile battery of a new antirocket missile defense system on Sunday on a dusty rise at the outskirts of this southern Israeli city after a week of heightened tensions between Israel and Gaza.

Palestinian mourners carried the body of Saber Assalya, an Islamic Jihad militant, during his funeral in the northern Gaza Strip on Sunday. Increased tensions between Israel and Gaza have led to fears of an all-out confrontation.

Military officials said the deployment was accelerated because of the recent escalation in rocket and mortar fire by Gaza militants against southern Israel and Israeli airstrikes on Gaza, which have led to fears of an all-out confrontation. But Israeli officials warned that the system, known as Iron Dome, was still experimental and could not provide the country with full protection from approaching rockets.

The situation along the border remained volatile. On Saturday, Gaza-based militant groups met and agreed to restore an unofficial cease-fire, according to officials from Hamas, the Islamic militant group that controls Gaza. The cease-fire has largely held since the end of Israel’s three-week military offensive in Gaza in the winter of 2008-9. That war came after years of rocket fire against southern Israel.

On Sunday morning, however, hours before Iron Dome became operational, an Israeli drone fired a rocket at a car in northern Gaza, killing two militants from the organization Islamic Jihad.

Israel said the militants were on their way to fire a rocket at its territory. Islamic Jihad, which has played a significant role in the recent violence, said the two were members of its military wing. The group said it reserved the right to respond against Israel for the attack.

Prime Minister Benjamin Netanyahu of Israel said Sunday that he did not want to “foster the illusion” that Iron Dome would “provide a complete or comprehensive answer” to the rocket threat. “Iron Dome is still in the experimental stage, and we do not have the possibility of deploying batteries to protect every home, school, base and installation,” he said.

At least two Katyusha-type rockets were fired out of Gaza last week at Beersheba, a city of approximately 200,000 people about 25 miles southeast of Gaza. One struck a street in a residential area in the center of the city, wounding one man.

The first battery was placed just north of this city in the Negev Desert. Briefing reporters at the site against a backdrop of apartment buildings in the distance, Brig. Gen. Doron Gavish, the commander of the air defense corps of the Israeli Air Force, said the mobile battery was built to be easily disassembled, and would be deployed at a variety of sites in southern Israel in the coming weeks as part of an evaluation.

Developed over more than three years by Rafael Advanced Defense Systems Ltd., an Israeli company, Iron Dome is meant to intercept and destroy rockets with radar-guided missiles. Citing security reasons, military officials declined to provide operational details.

Residents of Beersheba generally have about 45 seconds to take cover when a rocket alert is sounded. Iron Dome is designed to protect against mid-range rockets, like those that have struck Beersheba and the Israeli port of Ashdod, 20 miles north of Gaza. But the system is known to be ineffective against shorter range Qassam rockets and mortar shells fired from Gaza at Israeli border communities like Sderot.

Amir Peretz, a former Israeli defense minister and a resident of Sderot, said Sunday that 13 mobile batteries would be needed to cover southern Israel and the north, which was struck by thousands of rockets during Israel’s war against Hezbollah in 2006.

There has been public criticism of the Iron Dome program in Israel in recent months, with the major newspapers questioning why it had still not moved into operational field testing. Critics of the program have suggested a fear of failure, but public pressure seems to have moved up the schedule.

There is also a matter of cost. Many of the rockets fired out of Gaza are crude and cheaply produced, whereas estimates of the cost of each missile fired to intercept a rocket range from $25,000 to $100,000.

General Gavish said it was more important to consider the cost of not intercepting a rocket that hits a city, adding, “One cannot put a price on people’s lives.”