The arrest of three friends of the surviving suspect in the Boston Marathon bombing reminds us of the consequences of withholding information from investigators, lying or being an accessory after the fact for a friend or loved one.In other words, if the authorities are correct, “snitching” could have saved these three young men from facing criminal charges, international notoriety, and a future scarred by the coverup of their friend — a suspected terrorist.In some circles, the term snitch is used to intimidate good, law-abiding citizens from assisting law enforcement with information during investigations. But the arrest of the three University of Massachusetts, Dartmouth students underscores the importance of reporting suspicious activity to law enforcement authorities.More important, the investigation of the Boston Marathon bombings demonstrates that our struggle to combat terrorism greatly depends on public engagement.As the FBI pointed out immediately after the Boston attack, terrorists are somebody’s neighbor, co-worker, friend or relative. It’s clear that our safety depends on all of us reporting suspicious activities, regardless of the intimate relationship we may have with the people we suspect.While we don’t want to return to the days of the Red Scare, when many Americans lived in fear of being falsely accused of having communist ties, we cannot become complacent.Since 9-11, many of us have become detached from the reality that terrorists continue to organize, train and scheme to harm the U.S. and its people. But there have been more than 50 known terror plots against the United States since 9-11.While counterterrorism efforts have prevented these attacks, the Boston bombings reveal it will take continued effort by all of us to keep our communities safe.The government’s “If you see something, say something” campaign should remind those who remain apathetic about their important role in the “war on terror.”My future, your future and our children’s future depend on public involvement in this struggle.We were reminded of this integral partnership in the moments right after the Boston bombings, when the FBI sought the public’s involvement by establishing an 800 number and asked for tips, videos and pictures.A public tip led to Dzhokhar Tsarnaev’s capture after a city shutdown was lifted.Public involvement stopped the 2009 Christmas Day bomber who tried to detonate a bomb in his underwear on a flight from Amsterdam to the U.S.The public helped prevent the 2001 shoe-bomb attack by Richard Reid, who hid and attempted to light explosives inside his shoes on a flight from Paris to Miami.It was a New York T-shirt vendor who saw smoke coming from a Nissan SUV and alerted local cops to thwart the would-be 2010 Times Square car bomb.Too many of us have a false sense of security and are uninterested in the difficult efforts needed to maintain the safety and protection of the nation. I have seen this apathy first-hand for the past eight years as a homeland security professor. I always remind students that no matter your vocation, religion or race, homeland security should be of interest because it affects all of us. Our futures are inextricably linked in this struggle to combat extremism.There are several lessons to be learned from the Boston bombings. But if we learn nothing else as citizens, it should be that the key to winning this “war on terror” will be our deliberate, persistent and unconditional public engagement. Herma Percy, a member of the Anti-Terrorism Advisory Council of Maryland, is homeland security program director at Washington Adventist University in Takoma Park, Md. She wrote this for the Baltimore Sun. firstname.lastname@example.org.