So far, the United States has provided $205 million to support the Iron Dome, manufactured by Israel's state-owned Raphael Advanced Defense Systems Ltd. The system uses small radar-guided missiles to blow up in midair Katyusha-style rockets with ranges of 3 miles (5 km) to 45 miles (70 km), as well as mortar bombs.
But top Republicans have criticized President Barack Obama for what they described as inadequate funding of US-Israeli missile defense cooperation in his 2013 budget request released in February amid deficit-reduction requirements.
Legislation moving through the Republican-controlled US House of Representatives would give Israel additional $680 million for the Iron Dome system through 2015, and some House lawmakers are seeking a deal with Israel to share production of the Iron Dome system with U.S. weapons manufacturers.
Obama's fiscal 2013 budget request calls for $3.1 billion in security assistance to Israel, part of a 10-year, $30 billion U.S. commitment, none of which was scheduled to fund Iron Dome.
On Thursday, Panetta said the Pentagon would seek additional funding for the Iron Dome program over the next three years "based on an annual assessment of Israeli security requirements."
"My goal is to ensure Israel has the funding it needs each year to produce these batteries that can protect its citizens," Panetta said.
He said the $70 million would be provided this fiscal year, which ends in September.
"This is assistance that, provided Congress concurs, we can move quickly, to ensure no shortage in this important system," Panetta said in a statement after meeting Israeli Defense Minister Ehud Barak at the Pentagon.
The pro-Israel lobby group AIPAC welcomed Panetta's decision, saying it would help Israel better protect its citizens against some 60,000 missiles and rockets amassed at its borders by Hamas and Hezbollah Islamist militants.
As of April, Israel had deployed three operating units of the system, which helped thwart Palestinian rocket salvos during a flare-up in fighting around the Gaza Strip in March. It has spoken of needing a total of 13 or 14 units to protect various fronts.
The system intercepted more than 80 percent of the targets it engaged in March when nearly 300 rockets and mortars were fired at southern Israel, saving many lives, a US Defense Department spokesman said on March 27.