The US government released a once-classified chapter of a congressional report about the attacks of Sept. 11, 2001, that questions whether Saudi nationals who were in contact with the hijackers after they arrived in the U.S. knew what they were planning.

Later investigations found no evidence that the Saudi government or senior Saudi officials knowingly supported those who orchestrated the attacks. But lawmakers and relatives of victims, who don't believe all Saudi links to the attackers were thoroughly investigated, pushed for more than 13 years to get the pages released.

Former President George W. Bush classified the chapter to protect intelligence sources and methods and perhaps to avoid upsetting Saudi Arabia, a close U.S. ally. President Barack Obama ordered a declassification review of the chapter, which Congress released on Friday.