As the seventh anniversary of the 7/7 London terrorist attacks recently came to pass, we were reminded by a series of events across the U.K. that the persistent threat from terrorism remains.

In the shadow of the impending Olympics, a mere three weeks away, such reminders compel both our nation’s homeland security apparatus as well as the general public to remain vigilant against an evolving, asymmetrical terror threat.

Few forums offer as attractive a target to militant organizations and radicalized individuals as the Olympic Games. In London, more than 10 million people are expected to attend the games and related festivities, with several hundred million more watching on television throughout the world.

This naturally places London’s counterterrorism and national security personnel on high alert, and recent events seem to justify such a high level of preparedness.

A 24-year-old man, known only by the initials CF, was recently charged by British authorities for violating the terms of a legal order related to a previous charge of traveling to Somalia to train with Islamist militants.

The man, known to be associated with the al-Qaeda-linked Somali terrorist organization al Shabaab, had been restricted from traveling through parts of London near Olympic Park. It was determined through a review of an electronic monitoring bracelet worn by the man that he had violated his travel restrictions no fewer than five times between April and May.

Whether CF was traveling through the Olympic Park area with malicious intent is unknown; however, his apprehension does caution against complacency. Several other recent events amplify that message.

As Heritage’s Luke Coffey recently said, “British intelligence sources believe that there are at least 200 potential terrorists actively planning suicide attacks in the U.K. Rather than targeting Olympic venues, where the security presence will be extremely high, it is thought that potential attackers will focus on less secure areas with large crowds, such as train stations and open-air television screenings.”

No amount of money and no number of security personnel can provide an absolute blanket of protection to all areas in and around the Olympics. Each and every person attending the games and within the surrounding areas must be responsible for observing and reporting on suspicious activity. In so doing, the public itself plays a crucial role as a force multiplier, helping to lessen the chances of a successful terrorist event.

Although thousands of miles away, the upcoming Olympics should serve as a reminder to those here in the U.S. that the threat of terrorism remains. Public awareness and vigilance remain a key component of a comprehensive homeland security strategy. The Olympics are merely the latest test in the struggle against radicalism and violence—neither the beginning nor the end of the ongoing threat.