After days of controversy, the U.S. House of Representatives has authorized $1 billion in additional funding for Israel's Iron Dome missile defense system.

The funding for the aerial defense system was originally included in the must-pass legislation that the House discussed earlier this week, but it was removed from the final version to appease a number of progressives who threatened to kill the legislation unless the funding was withdrawn.

The bill will now be let into the Senate, where it is unknown when it will be voted on.

House Majority Leader Steny Hoyer introduced a separate bill to the floor on Thursday under suspension, which bypassed the usual processes for passing the bill and required a two-thirds majority to pass.

With two present, the final vote was 420-9. Eight Democrats and one Republican voted against the bill.

The decision comes as the debate over U.S. support for Israel heats up, with a growing number of progressive voices in Congress urging President Joe Biden to condition US assistance to Israel on the country's human rights record.

Supporters of the funding say it is intended to "replenish" the Iron Dome batteries following the recent fighting in Gaza, but the $1 billion passed by the House on Thursday represents a considerable increase in U.S. support for the program.

Israel receives $3.8 billion in military support from the United States each year, as outlined in a 10-year memorandum of understanding (MoU) signed by President Barack Obama in 2016. Every year, $500 million is allocated to missile defense.

In 2020, Congress appropriated $73 million for the Iron Dome, one of several missile defense programs.

The Iron Dome Aerial Defense System is designed to intercept rockets in mid-flight - by targeting them and firing interceptor missiles to destroy them - before they can strike Israeli residents. It was first created by Israel's Rafael, a defense technology company, but the system has subsequently been significantly funded by the U.S.

Israel's Prime Minister, Naftali Bennett, commended both parties for their commitment to the country's security, as well as the American people for their "steadfast friendship."

U.S. Defense Secretary Lloyd Austin also spoke via phone with his Israeli counterpart Benny Gantz, discussing "regional developments, including the need to stop the Iranian nuclear program from advancing," the Pentagon said in a statement.