Coinciding with Attorney General Eric Holder telling ABC News this week that "the American people would be surprised by the depth of the [homegrown terrorist] threat” while discussing his growing concern about Americans becoming radicalized and turning to terrorism, Homeland Security Secretary Janet Napolitano told the Council on Foreign Relations that it is incumbent citizens pay attention to their surroundings for anything suspicious and out of place, and to report it to proper authorities. It might just prevent a domestic terrorist attack, she said.

“With respect to individuals and the private sector, we're taking a much closer look at how we can support and inform our greatest asset, individual citizens, and with them the private sector. You are the ones who know if something is not right in your communities, such as a suspicious package or unusual activity,” Napolitano said.

Napolitano said “three years ago, it was an attentive store clerk who told authorities about men trying to duplicate extremist DVDs. This led federal agents to eventually round up a plot to kill American soldiers at the Fort Dix army base here in New Jersey.”

And “just last month, a passenger saw two employees exchange a bag at the Philadelphia airport that had not been properly screened. That passenger's vigilance ultimately stopped a gun from getting onto the plane.”

"For too long, we've treated the public as a liability to be protected rather than an asset in our nation's collective security," Napolitano confessed.

"There's actually an important role we can play in educating even our very young about watching for, and knowing what to do, if you're in an airport and you see a package left with no one around," Napolitano said.

But using citizens as an extension to create wider situational awareness to potential threats is not a new approach. Several years ago, Robert David Steele, an outspoken veteran intelligence officer, told HSToday.us that “50 percent of the ‘dots’ that prevent the next 9/11 will come from bottom-up [local] level observation” and unconventional intelligence from “private sector parties.”

Lynda Howes, a civilian member of the emergency event and management unit of the Calgary (Canada) Police Service, told colleagues at a conference last summer that counterterrorism is only manageable if it is tackled at the grass roots level. She explained that it’s vital that everyone - including the public, the police, government and private industry – recognizes the potential indicators of terrorism and what actions to take if, and when, they are encountered.

Napolitano said while law enforcement “play[s] an absolutely critical role,” they also can “act on information they receive from individuals in the community,” in addition to “their own observations.”

Indeed. A tip from a citizen to the Oklahoma City police led to the responding officer – new on the job and having just received training in how to spot potential terrorist threats, arresting a man with a semi-automatic weapon … and a bomb!

“The capacity to recognize indicators of criminal activity, the ability to interact with the people they serve in a productive way, the engagement of members of the community as informants or cooperating individuals all are critical in identifying terrorism warnings and indicators as well as criminal enterprises and emerging crime problems,” wrote former FBI counterterrorist David Cid, deputy director of the Memorial Institute for the Prevention of Terrorism that provided the Oklahoma City police department with the training the officer employed, in a recent HSToday.us “Best Practices” report.

Cid explained that “the terrorist is constrained by the same laws of physics that we all are. And in order to commit an act of terrorism he must engage in certain preparatory actions such as acquisitions of materials, target surveillance, recruitment of talent and so on.”

“These preparatory behaviors, if identified, recognized and acted upon in a timely way present the best opportunity to disrupt the terrorism planning cycle and to prevent an attack,” Cid continued. “Looking at the world through the lens of a counterterrorism practitioner, the police officer becomes a member of the counterterrorism cadre and force multiplier for federal law enforcement, which is highly competent, but heavily burdened. And by improving the quality, quantity and timeliness of field reporting, all aspects of policing are improved. The training lifts all boats.”

Former New Jersey counterterrorism chief Steve Serrao earlier told HSToday.us that it’s the cop on the beat, the fire investigator sifting through the ashes of a fire or the state trooper making a routine traffic stop that could spot indications of potential terrorist plots - especially if their daily tips and leads are cross-referenced with federal intelligence and a state's or region's intelligence fusion center.

But “the challenge is not just using federal power to protect the country, but also enlisting a much broader societal response to the threats that terrorism poses,” Napolitano stated, adding that there’s an “urgent need to refocus our counterterror approach to make it a shared endeavor - to make it more layered, networked and resilient - to make it smarter and more adaptive and to make sure that as a country … we are at the point where we are in a constant state of preparedness and not a state of fear.”

“We do it with four levels of collective response,” Napolitano explained. “It starts with the American people. From there, it extends to local law enforcement, and from there up to the federal government, and then finally out beyond our shores, where America's international allies can serve and do serve as partners in a collective fight against terrorism.”

"So I think better education about the breadth of the threat and how it can be carried out is important,” Napolitano stated.

And even though “it’s gotten a whole lot harder for a terrorist to conduct the kind of conspicuous physical surveillance of a target that’s necessary for conducting a large-scale or mass casualty attack,” John Bumgarner, an 18-year veteran of special operations who has worked with most of the three-letter intelligence agencies at one time or another, told Homeland Security Today for its April 2008 cover story, “Every Eye A Spy,” counterterrorism experts said there are indications of terrorist plotting that citizens can be taught to be aware of.

"Every terrorist act is preceded by observable planning activities. When troops and citizens know what to look for and how to report suspicious activity, terrorist acts can be prevented,” stated a late 2002 Air Force's Office of Special Investigations memo about  “Eagle Eyes,” a program to "deter terrorism by recognizing and reporting pre-attack activities.”

A year ago the Nevada Department of Homeland Security and the University of Nevada, Los Vegas Institute for Securities Study started distributing the DVD, “Seven Signs of Terrorism,” to groups and individuals most likely to be in a position to observe the signs of a potential terrorism plot.