By the CNN Wire Staff
May 6, 2011 -- Updated 1641 GMT (0041 HKT)
CNN looks back at the decade-long hunt for Osama bin Laden in the award-winning documentary "In the Footsteps of bin Laden" at 11 ET Friday night.
(CNN) -- Saber-rattling al Qaeda warnings against the United States emerged Friday as Osama bin Laden's killing yielded a trove of ominous intelligence, including details about a possible attack on the 10th anniversary of 9/11.
Al Qaeda, the bin Laden terror network that masterminded the deadly attack on the U.S. 10 years ago, confirmed its leader's death on Friday in a Web statement, using that opportunity to taunt and threaten the United States.
"Sheikh Osama didn't build an organization that will vanish with his death or fades away with his departure," according to the statement, which CNN could not independently authenticate.
The statement, which congratulates the "Islamic Nation on the martyrdom of their devoted son Osama," repeated themes and threats made over the years in al Qaeda statements, before and after the September 11, 2001, attacks.
"The blood of the mujahed sheikh, Osama bin Laden, may God have mercy on him, is very dear to us and more precious to us and to every Muslim from being shed in vain," the statement said. A mujahed is defined as a Muslim engaged in what he considers to be jihad.
"This blood will be a curse that will chase the Americans and their agents, a curse that will pursue them inside and outside their country, and soon -- with God's help -- we pray that their happiness turns into sorrow and may their blood mix with their tears and let Sheikh Osama's resonate again."
Al Qaeda frequently cites the Israeli-Palestinian conflict in its pronouncements, and it did so again, saying America "will neither enjoy nor live in security until our people in Palestine live it and enjoy it."
"The soldiers of Islam in groups and as individuals will continue to plan and plot without any fatigue, boredom, despair, surrender or indifference until you receive from them a cunning misfortune that will gray the hair of the child even before he gets old," the statement said.
Pakistanis were urged to revolt and "rise up," cleansing the "disgrace that was brought upon them by a handful of traitors and thieves" and "their country from the filth of the Americans who have wreaked havoc in the land."
The statement surfaced as protesters packed the streets of Abbottabad -- where bin Laden was shot and killed -- in a rally organized by Jamrat-E-Islami, Pakistan's largest Islamist party. The demonstrators denounced the U.S. and Pakistani governments.
Also, the statement disdained the United States, both its efforts and its motives, saying that the Americans managed to kill bin Laden "by disgrace and betrayal." Bin Laden was slain in a U.S. Navy SEAL raid on a compound early Monday in Abbottabad, a military garrison town north of the capital of Islamabad.
"Men and heroes only should be confronted in the battlefields but at the end, that's God's fate. Still we ask, will the Americans be able through their media outlets, their agents, their instruments, soldiers, intelligence services and their might be able to kill what Sheikh Osama lived for and was killed for? How far! How impossible!"
After bin Laden was shot and killed, he was buried at sea in what U.S. officials described as a proper Islamic burial.
But the statement said if Americans treat the bodies of bin Laden or his family members improperly, either dead or alive, or do not hand over the bodies to families, there will be retribution.
"Any offense will open unto your doors of multitudes of evil for which you will only have yourselves to blame."
According to the statement, bin Laden recorded an audio message one week prior to his death, regarding the revolutions sweeping the Muslim world and offering advice and guidance. Al Qaeda indicated that the release of this message is forthcoming.
Meanwhile, investigators poring over material seized in the Monday raid found details about a possible attack on the 10th anniversary of 9/11, and the intelligence led to a nationwide alert regarding rail security.
As early as February 2010, al Qaeda members discussed a plan to derail trains in the United States by placing obstructions on tracks over bridges and valleys, the alert said, according to one law enforcement official.
The plan was to be executed later this year, coinciding with the 10th anniversary of the September 11 attacks, though no specific rail system was identified, the official said.
The Department of Homeland Security confirmed a notice went out to federal, state, local and tribal authorities.
"We have no information of any imminent terrorist threat to the U.S. rail sector, but wanted to make sure our partners are aware of the alleged plotting; it is unclear if any further planning has been conducted since February of last year," spokesman Matt Chandler said.
Rail agencies across the United States were taking no chances.
The Chicago Transit Authority re-issued security bulletins, "reminding employees of what activities to look for and what steps to take should they encounter any suspicious or criminal activity during the course of their duties," said Wanda Taylor, a CTA spokeswoman.
Amtrak employees also were on a heightened "state of vigilance," said spokesman Marc Magliari.
A U.S. official said that "valuable information has been gleaned already" from the cache gathered at bin Laden's compound, though no specific plots or terrorist suspects were identified.
But the material suggests that al Qaeda was particularly interested in striking Washington, New York, Los Angeles and Chicago, according to the law enforcement official who spoke on condition of anonymity.
U.S. authorities have found that al Qaeda appears especially interested in striking on significant dates like July 4, Christmas and the opening day of the United Nations.
The cache from the compound included audio and video equipment, suggesting bin Laden may have taped makeshift messages there, a U.S. official said.
Ten hard drives, five computers and more than 100 storage devices, such as disks and thumb drives, were also found, a senior U.S. official told CNN.
The Washington Post reported on Thursday that the CIA had a safehouse in Abbottabad "for a small team of spies" who performed surveillance on the compound.
Citing U.S. officials, the effort "relied on Pakistani informants and other sources to help assemble a 'pattern of life' portrait of the occupants and daily activities at the fortified compound where bin Laden was found."
It was "mobilized after the discovery of the suspicious complex last August that involved virtually every category of collection in the U.S. arsenal, ranging from satellite imagery to eavesdropping efforts aimed at recording voices inside the compound," the Post reported.
Dozens of people in Abbottabad have been arrested because of their suspected connections to the compound where Osama bin Laden was shot and killed, a Pakistani intelligence official said Friday. Investigators want to know whether any of the people are al Qaeda members or sympathizers.
The United States and Pakistan have been allies in the war on terror for years, but there have been strains lately over suspected U.S. drone attacks killing innocent civilians and American concerns that Pakistanis haven't been robust enough in the fight against Islamic militants. Another suspected drone strike killed 12 suspected militants on Friday in the Pakistani tribal region.
Questions in Washington remain over why and how Pakistani intelligence officials could not have known bin Laden was hiding out in a compound in the city, which has a military academy and a strong military presence.
Pakistani armed forces chiefs issued a statement Thursday admitting that there had been "shortcomings in developing intelligence" on the terror leader's presence in the country.
The army chief of staff, Gen. Ashfaq Parvez Kayani, also "made it very clear that any similar action, violating the sovereignty of Pakistan, will warrant a review on the level of military/intelligence cooperation with the United States," the statement said.
Pakistan has ordered U.S. military personnel on its territory drawn down to the "minimum essential" level in the wake of the raid, the statement said.