On May 18, a carrier ship bound for the Port of New Orleans left a Caribbean nation weighted with 12,000 tons of ammonium nitrate. Intelligence later revealed that two of the ship’s crew members were on terrorist watch lists. Meanwhile, a few miles outside New Orleans, police received a report of someone suspiciously circling a chemical plant in a car while taking pictures.

What may have appeared at first to be isolated incidents were actually parts of an elaborate drill to test how well local, state, federal, and even international emergency responders would coordinate and communicate in the fog of an unfolding terror plot. The mock scenario, which played out in a day-long tabletop exercise in New Orleans last May, was a cascade of escalating disasters that involved the revelation of the plot, multiple shootings, a chemical leak, hostage-taking, and the release of nuclear radiation. The object of the exercise was to overwhelm the region’s elaborate web of responders and investigators and force them to turn a critical eye to how prepared they are for a real disaster involving weapons of mass destruction, or WMD.

“We are training to identify what the WMD threat is around the critical infrastructures and around our key resources,” said John Perren, assistant director of the FBI’s Weapons of Mass Destruction Directorate, which sponsored the three-day training workshop. “What we do is we identify what our roles are, what our responsibilities are, and how we bring that to the table as a force-multiplier to handle this WMD.”

The workshop is a prime illustration of the WMD Directorate’s mission, which is to prevent a weapon of mass destruction—chemical, biological, radiological, nuclear, or explosive—while at the same time preparing to respond to one. The preventive pieces, or countermeasures, include creating and nurturing relationships with experts in the field—scientists, law enforcement partners, the private sector—so they know how to recognize suspicious activity and how to report it.

“Together, we form strategic partnerships,” said Perren, who attended the training. “We identify the gaps. We identify the vulnerabilities. Together, we develop a plan—a mitigation—to address that vulnerability or that gap.”

New Orleans provided a challenging backdrop—it has one of the country’s busiest ports and other critical infrastructures like chemical and power plants that would set off a disruptive ripple effect if attacked. The city, which weathered the real-life disaster of Hurricane Katrina in 2005, is host to the 2013 Super Bowl. Workshop participants, including attendees from the Department of Homeland Security, the U.S. Coast Guard, and the Department of Defense, along with scores of state and local agencies, said the mock scenario helped them refine their preparedness plans.

“It opens everyone’s eyes to what the threats and hazards are,” said Lt. Eric Acosta, a fire safety officer at a port outside New Orleans. “And everyone knows everyone so it’s not like, ‘Who’s he?’ when something happens.”

That was a key take-away from the training—having strong working relationships in place makes for a smoother response to any emergency, whether it’s with first-responders or company CEOs. It’s why the FBI has designated WMD coordinators in its 56 field offices—to knit a fabric of connections in their respective regions.

“You play how you practice,” said Stephanie Viegas, a special agent and WMD coordinator in our Miami Field Office, who attended the workshop. “The time to get to know each other is not when something’s happening. It’s having meetings together, going over each other’s operational plans, getting together, and training together so we have the opportunity to recognize and address any gaps.”

In the mock terror scenario, each escalating event prompted a round of questions over who was supposed to do what. Could it have been prevented?

“What keeps me up at night is not what I know—it’s what I don’t know,” said Perren. “And that’s why we do these things: to establish tripwires to find out what we don’t know.”