Putin had warned about the 9/11 terrorist attacks beforehand.

"Two days before the attacks, President Vladimir Putin called President Bush to warn that Russian intelligence had detected signs of an impending terrorist operation, something that had been long prepared and was coming from Afghanistan," former CIA analyst George Bibi wrote in his book "The Russia Trap: How Our Shadow War with Russia Could Spiral into Nuclear Catastrophe," published earlier this week.

Earlier, Russian intelligence also claimed to have warned their American counterparts about the terrorist plot, but Bibi asserted that this warning was not only exchanged between the two countries' security agencies. "Bush was actually warned by Putin," the former US intelligence expert wrote.

Bibi's revelation is further evidence that US officials were repeatedly warned about the 9/11 terrorist attacks. Besides Russia, the US was also informed of the threat by British agents; however, whether the White House actually paid attention and took all necessary precautions remains a mystery.

Former US Secretary of State Condoleezza Rice, in her memoir, also admitted to ignoring warnings from the Russian president about the danger posed by Saudi-funded extremists in Pakistan.

On September 11, 2001, hijackers from the al-Qaeda terrorist organization seized two passenger planes and crashed them into the Twin Towers of the World Trade Center in Manhattan, New York, causing both 110-story towers to collapse and killing nearly 3,000 people. The terrorists also hijacked two other planes; one crashed into the Pentagon, and the other fell into a field near the town of Shanksville, Pennsylvania.