Democratic presidential candidate Bernie Sanders urges the United States to address the “root cause” of the September 11, 2001 attacks, voicing support for Senate legislation that would allow families of terror victims to sue Saudi Arabia in federal court.

“I think there's a lot about Saudi Arabia that we don't fully understand. And I want to get to the root cause of it. The root of what Saudi Arabia has done,” Sanders said on NBC News’ “Meet the Press” aired Sunday.

The Vermont senator said that Saudi money is “going all over the world” to fund extremism. “And I think that the full extent of the role that Saudi Arabia plays in supporting extremism in this world is something that we should explore.”

There is “some evidence - and we will have to ascertain whether it's accurate or not - that money from Saudi Arabia actually funded a 9/11 attack,” he said.

The remarks come as Congress is considering legislation, called the Justice Against Sponsors of Terrorism Act, that would allow families of 9/11 victims to hold any foreign government or entity, including Saudi Arabia, accountable in US courts for any role in the attacks.

A file photo of the 9/11 attacks in New York

Saudi Arabia has threatened that it will sell off $750 billion in American assets if the bill is passed.

President Barack Obama has indicated that he will veto the bill if it came to his desk, arguing that the measure would open the floodgates to lawsuits against the US government by individuals in other countries.

The Obama administration has come under intense pressure by a bipartisan group of lawmakers to declassify 28 pages of a 2002 congressional report that could implicate Saudi officials in the 9/11 attacks.

A group of families who lost loved ones in the 9/11 attacks wrote a letter to President Obama last week, saying there was “no excuse for refusing to reveal the truth, whatever it may be.”

Sanders has called for the declassification of the redacted pages.

Former US Sen. Robert Graham, co-chairman of the joint congressional commission that wrote the full 838-page, recently told CBS's “60 Minutes” that the 9/11 hijackers were “substantially” supported by elements within the Saudi government, as well as rich Saudi individuals and charities.