The Pentagon is planning to help Israel buy four more Iron Dome short-range anti-rocket batteries, the head of the Pentagon's Missile Defense Agency said on Wednesday.

Budge Approval US to help pay for Iron Dome Yitzhak Benhorin Democrats, republicans slated to approve 2011 budget this week enabling Obama to increase security aid to Israel, transfer $205 million for development of anti-missile system US to help pay for Iron Dome

"In our budget, we have a proposal to assist with procurement of four more batteries," Army Lieutenant General Patrick O'Reilly, the agency's director, told the US Senate Appropriations Defense subcommittee.

The batteries consist of a mobile air defense system with a radar-guided interceptor missile launched from a truck-sized firing platform.

O'Reilly was referring to fiscal 2011 funding of $203.8 million added last June at the request of President Barack Obama, agency spokesman Richard Lehner said in an email. The goal was to spur production and deployment of the system, the first direct US investment in the project.

Israel began deploying $50-million Iron Dome units two months ago to counter Katyusha-style rockets fired at population centers from Palestinian territory. The first was set up near Beersheba, a southern city twice hit by rockets during a March flare-up of cross-border violence.

A second was deployed last month to the coastal city of Ashkelon, north of the Gaza Strip ruled by Hamas.

On April 7, the system successfully intercepted a rocket from Gaza for the first time, followed by at least seven other intercepts, the Israeli military said. Its development was spurred by the 2006 conflict with Hezbollah in Lebanon and the Gaza Strip war against Hamas in 2008 and 2009.

'Iron Dome highly effective'

O'Reilly said he considered Iron Dome to have been "highly effective" in combat. But Israel faced a "daunting task" because of the volume of short-range rockets and missiles it faces, he said.

"This is one which the United States benefits from understanding and studying exactly how they've been successful with the Iron Dome system," he said. US troops could face similar threats from a combat zone, O'Reilly added.

Obama in his 2012 budget request asked the US Congress for $106.1 million for US-Israeli joint missile defense programs, including improvements to the Arrow ballistic missile shield and David's Sling. Unlike these two programs, the development of Iron Dome was a unilateral Israeli project.

The Iron Dome's radar-guided interceptor missile is built by state-owned Rafael Advanced Defense Systems Ltd. It is designed to destroy in mid-air rockets and mortar bombs that have ranges of 5 km (3 miles) to 70 km (45 miles).

Declassified video of two Iron Dome intercepts was screened in Washington this week at the annual policy conference of the American Israel Public Affairs Committee, a pro-Israeli lobby group.