Terry Strada, whose husband Tom Strada died in the Twin Towers, unleashed a stinging attack on Riyadh, accusing it of complicity in the attacks, and denouncing former presidents who were in attendance.

"You are missed more with each year that passes, but how can it be 25 years and still we have no justice for the role that Saudi Arabia played in your murder?" she said.

The 11 September 2001 attacks were carried out by mostly Saudi hijackers and orchestrated by Al-Qaeda leader Osama bin Laden, a wealthy Saudi.

"For 25 years, administration after administration -- including leaders in front of us here today -- chose to protect the Saudis instead of standing with a 9/11 family," Strada said, calling for action from the absent Trump.