The defense appropriations bill agreed to by lawmakers this week calls for US funding for Israel’s Iron Dome missile defense system to double, bringing Washington’s investment in the program to over $1.2 billion since 2011.

House appropriators — like a Senate version of the bill hashed out earlier this year — added $175 million to the Obama administration’s original request, bringing the total to $350 million in the fiscal year 2015 bill.

But a key part of the American participation in the program hinges on the stipulation that 55 percent of the components be made in the US, with the rest being produced in Israel by Rafael Advanced Defense Systems. […]