US President Barack Obama has criticised the US Senate’s decision to reject his veto of legislation allowing relative of 9/11 victims to sue the Saudi government.
Mr Obama described the move overturning his veto as a “mistake” and “basically a political vote”.
He also criticised some senators – although not by name – for acknowledging they had originally voted for the bill without knowing its contents.
White House spokesman Josh Earnest described it as “the single most embarrassing thing this United States’ Senate has done possibly since 1983”.
He was referring to the last occasion when the chamber voted overwhelmingly to override a presidential veto.
Victims’ families say they are still seeking justice 15 years after the attacks that killed nearly 3,000 people.
The bill permits them to sue the Saudi government for the kingdom’s alleged backing of the 19 hijackers involved. Fifteen were Saudi nationals.
Senators voted 97-1 to override President Obama’s veto, with the lone “no” vote being cast by Senate Minority Leader Harry Reid.
The bill will become law if it also wins the backing of Congress.
In a letter to Senate leaders, President Obama said the bill would erode sovereign immunity principles that prevent foreign litigants “from second-guessing our counter-terrorism operations and other actions that we take every day”.
But one of the bill’s leading proponents, Senator John Cornyn, dismissed his concerns as “unpersuasive”.
Sen Cornyn and other supporters said the bill is narrowly tailored and applies only to acts of terrorism that occur on US soil.
“This bill is about respecting the voices and rights of American victims,” he said.
The families and their lawyers have dismissed concerns over the legislation as “fear-mongering”.
Saudi Arabia, which denies any involvement in the September 11 attacks, and its allies have warned they will take retaliatory action if the bill is passed.
It is believed this could include curtailing official contacts, pulling billions of dollars from the US economy and restricting US access to strategic regional air bases.
“This should be clear to America and to the rest of the world: When one (Gulf) state is targeted unfairly, the others stand around it,” said Abdulkhaleq Abdullah, an Emirati Gulf specialist.
“All the states will stand by Saudi Arabia in every way possible.”