The US House of Representatives unanimously voted Sept. 9 to allow the families of victims of the Sept. 11, 2001, terrorist attacks to sue Riyadh in US court, defying President Barack Obama and an army of Saudi lobbyists. The voice vote follows similar action by the Senate in May and sends the bill to Obama, who now has to decide whether vetoing the popular bill is worth the political cost.

The White House has objected to the legislation for years on the grounds that weakening sovereign immunity protections could hurt the United States' ability to conduct foreign policy. Current and former government officials have also warned that other countries may retaliate, putting US troops and diplomats in harm's way for their actions abroad.

One aspect that has received far less attention, however, is the potential impact on the assistance that Washington provides to Riyadh. The State Department requests — and Congress approves — a token $10,000 in military training every year, but the heart of the relationship is America's massive weapons trade with Saudi Arabia: a record-shattering $115 billion approved and pending arms deals under Obama, according to a new report by the nonprofit Security Assistance Monitor.

On the face of it, those sales could legally continue even if the bill becomes law and a court eventually finds in favor of the plaintiffs. The Arms Export Control Act of 1976 prohibits arms and munitions transfers to countries that support acts of international terrorism, but leaves it up to the secretary of state — not the courts — to make that determination.