Why are 28 pages of the Joint Congressional Investigation into 9/11 still classified?

Following the terrorist attacks on September 11, 2001, Congress set up a joint committee to investigate. After nearly 6 months, the joint committee released its report - but the Bush administration redacted 28 pages of the report, citing the damage the information could do to our relationships with foreign governments. --Ever since then, families of the victims of 9/11, lawmakers, and government watchdog groups have all been agitating for the declassification of those 28 pages. First the Bush administration, and then the Obama administration have refued all requests to reveal what's in those 28 pages. President Obama told the families during a 9/11 memorial service that he would release the information, only to reneg on that promise.

Read more at the American Thinker
(Hat tip: KimR)