The Israeli military rushed a fifth Iron Dome anti-missile battery into service on Saturday and deployed it in the Tel Aviv area, the army said, underscoring concerns over the range of Palestinian rockets.
Islamist militants in the Gaza Strip have fired three rockets at Tel Aviv in the past 48 hours. No one was injured and no damage was reported, but the fact that Israel's commercial capital is in the firing line has alarmed many Israelis.
The fifth Iron Dome was not scheduled to come into service until early 2013.
The four other batteries are all deployed much further to the south, close to the Gaza border.
An army spokeswoman said that since the start of an Israeli offensive against militants in the Gaza Strip on Wednesday, Iron Dome has intercepted at least 222 incoming rockets -- a 90 percent success rate.
The missiles are only fired when the system calculates that the incoming rocket might hit a built-up area.
Iron Dome's manufacturer, Rafael Advanced Defense Systems Ltd, says it provides protection against incoming hostile rockets with ranges of between 5 km (3 miles) and 70 km (42 miles), as well as mortar bombs.
Iron Dome was first deployed in April 2011 when it was fielded outside the southern city of Beersheba and shot down its first real Gazan rocket.
The system is truck-towed for easy transport, and Israel says it needs 13 of them for satisfactory nationwide defence.
Iron Dome, along with Israeli ballistic missile shield Arrow, has received extensive support from Washington, which seeks both to reassure and restrain the Jewish state in the face of the nuclear advances of its arch-enemy Iran.