WASHINGTON -- Usama bin Laden was plotting an attack on U.S. trains on the upcoming anniversary of the Sept. 11 terrorist attacks, according to some of the first information gleaned from his compound, a U.S. official confirmed to Fox News.

But the planning was more aspirational than concrete, counterterrorism officials say, adding that they have no recent intelligence pointing to an active plot for such an attack.

Bin Laden, however, "was more actively involved in plots" and "he was not as removed from the plotting process" as conventional wisdom suggested, the official told Fox News.

Intelligence analysts hope that the data will lead to the "operational piece" in this case that would include Adnan Shukrijumah (a one-time legal permanent resident) and Ilyas Kashmiri, who was behind the heightened threat level in Europe last year as well as in Mumbai in 2008.

As of February 2010, the terror organization was considering plans to attack the U.S. on the 10th anniversary of the 9/11 attacks. One idea was to tamper with an unspecified U.S. rail track so that a train would fall off the track at a valley or a bridge, according to a joint FBI and Homeland Security bulletin sent to law enforcement officials around the country Thursday. The Al Qaeda planners noted that if they attacked a train by tilting it, the plan would only succeed once because the tilting would be spotted the next time.

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The warning, obtained by The Associated Press, was marked for "official use only."

Information on the train plot appears to be the first widely circulated intelligence pulled from the raid this week on bin Laden's secret compound in Pakistan. After killing the terror leader and four of his associates, Navy SEALs confiscated a treasure trove of computers, DVDs and documents from the home where U.S. officials believe the Al Qaeda chief had been hiding for up to six years.

Intelligence analysts have been reviewing and translating the material, looking for information about pending plots and other terror connections.

"While it is clear that there was some level of planning for this type of operation in February 2010, we have no recent information to indicate an active ongoing plot to target transportation and no information on possible locations or specific targets," the warning Thursday said.

The FBI and Homeland Security told local officials to be on the lookout for clips or spikes missing from train tracks, packages left on or near the tracks and other indications that a train could be vulnerable.

Homeland Security spokesman Matt Chandler said, "This alleged Al Qaeda plotting is based on initial reporting, which is often misleading or inaccurate and subject to change." He said the government has no plans to issue an official terror alert because of it.

An official with the Association of American Railroads said the organization has received warnings from the federal government and is sharing the information throughout the railroad network. "We are always making sure that the system is run as safely and securely as possible," the organization's spokeswoman, Patricia Reilly, said.

U.S. officials have disrupted other terror plots that targeted rails, including a 2009 plan to blow up the New York City subway system.

On Monday the FBI and Homeland Security warned law enforcement officials around the country that bin Laden's death could inspire retaliatory attacks in the U.S., and terrorists not yet known to the intelligence community could be operating inside the country. The transportation sector -- including U.S. rails -- remain attractive targets for terrorists.

Fox News' Catherine Herridge and The Associated Press contributed to this report.