In what may be the first warning to come from the intelligence haul at Osama Bin Laden's hideout in Pakistan, the feds are warning railroad interests about possible threats by terrorists.

Homeland security officials yesterday sent a bulletin to the railroad sector describing terrorist planning that was uncovered, indicating possible attacks to coincide with the 10th anniversary of the September 11th attacks later this year.

This was the statement released last night by Department of Homeland Security spokesman Matt Chandler:

"DHS issued an intelligence message May 5 to its federal, state, local and tribal partners about potential Al-Qa'ida contemplation in February 2010 of plots against the U.S. rail sector. For the same reason, the Transportation Security Administration will issue a bulletin to rail sector stakeholders. We have no information of any imminent terrorist threat to the U.S. rail sector, but wanted to make our partners aware of the alleged plotting; it is unclear if any further planning has been conducted since February of last year.

We want to stress that this alleged Al Qa’ida plotting is based on initial reporting, which is often misleading or inaccurate and subject to change. We remain at a heightened state of vigilance, but do not intend to issue an NTAS alert at this time. We will issue alerts only when we have specific or credible information to convey to the American public. Our security posture, which always includes a number of measures both seen and unseen, will continue to respond appropriately to protect the American people from an evolving threat picture both in the coming days and beyond.

Since Sunday, DHS and its partners have taken a number of actions, including but not limited to: reviewing protective measures for all potential terrorist targets, including critical infrastructure and transportation systems across the country; deploying additional officers to non-secured areas at our nation’s airports; and identifying any new targeting rules that should be instituted to strengthen the ways we assess the risk of both passengers and cargo coming to the United States. As always, we urge our state, local, tribal and private sector partners, as well as the general public, to remain vigilant and report any suspicious activity to federal, state or local law enforcement."

At a hearing earlier this week on terrorism and mass transit, TSA Director John Pistole acknowledged that rail stands out as a possible target in the United States.

"U.S. mass transit and passenger rail systems remain a target for terrorist groups and have been the subject of numerous plots in the United States, as well as attacks overseas," Pistole told lawmakers.

While Pistole ticked off a number of programs the feds have undertaken to help tighten security, the hard truth is that most mass transit and commuter rail systems in big cities are very vulnerable.

Take Washington, D.C., which has the Metro subway and commuter rail lines coming into the city from Maryland and Virignia.

Unlike airplane travel, it isn't possible to check everyone's bag before boarding a train or entering a train station.

And the tunnels and above-ground points of travel are too numerous to consider full-time security.

But so far, we have avoided any attacks.

It will be interesting to see what else comes out of the papers and computers of Bin Laden in the weeks ahead.