The money will help restock Israel’s Iron Dome, which has been credited with shooting down dozens of incoming rockets fired by Palestinian militants over three and a half weeks of war.
Today’s House of Representatives approval came just before members began their five-week summer break and two days after the Pentagon announced ammunition deliveries to the Jewish state – and as the planned 72-hour ceasefire between Israel and Hamas unravelled almost as quickly as it began.
The House’s 395-8 vote in favour followed Senate adoption of the legislation by voice vote earlier. The bill now goes to President Barack Obama for his signature.
At a White House news conference Mr Obama reiterated his support for Israel’s right to self-defence while urging greater protection for Palestinian civilians.
He cited Iron Dome as a concrete way the US was helping “make sure that Israel is able to protect its citizens”.
The Iron Dome system has emerged as a game-changer in the current round of violence, with Israeli officials quoting a success rate as high as 90%.
The system uses radar, advanced tracking technology and anti-missile batteries to follow the trajectory of an incoming rocket or mortar and determine if it is heading for a major population centre.
If an urban area is threatened, interceptors are fired to detonate in the air in close proximity to the missile. Projectiles not posing a threat are allowed to fall in empty fields.
The system targets short-range rockets with a range of 2-45 miles and interceptors cost as much 100,000 dollars (£59,500) each.
Shortly after the Gaza conflict erupted Mr Obama praised the missile defence systems as proof of America’s commitment to Israeli security. His administration sent the Israeli request to Congress for more Iron Dome money even as the president and secretary of state John Kerry have been seeking a humanitarian ceasefire.
Created by Israel’s Rafael Advanced Defence Systems, Iron Dome has enjoyed strong US technological and financial support.
Throughout its history the US has provided more than 700 million dollars (£416m) to help Israel cover costs for batteries, interceptors, production costs and maintenance, the Congressional Research Service said.
The total already appeared set to climb above the billion-dollar mark after Senate appropriators doubled the Obama administration’s request for Iron Dome funding for the 2015 financial year. Now it seems likely to rise even further, with Mr Obama expected to sign any bill swiftly into law.
It is unclear, however, how quickly the new supplies might reach the battlefield and Israel and Hamas may be in for a prolonged fight. A ceasefire arranged by the United States and United Nations collapsed shortly after its start yesterday morning.
More than 1,400 Palestinians, mostly civilians, and more than 60 Israelis, mostly soldiers, have been killed in the last 25 days.