Experts applauded the telecommunications giant for responding quickly to the explosion by deploying portable cellular sites to help restore some service. But they were alarmed by the widespread nature of the outages, both in terms of geography as well as the variety of services affected. Key to constructing systems that can withstand attacks and natural disasters — and recover quickly — is avoiding a single point of failure, they said.
“There’s a saying in security circles that if there’s no Internet ‘kill switch’ but you want to kill the Internet, kill the switching stations,” said Paul Rosenzweig, a former senior official in the Department of Homeland Security, referring to facilities that act as a node in a communications network, as the one in Nashville apparently did.
Suzanne Spaulding, who previously led the department’s efforts to secure critical infrastructure, said she was troubled by the disruption to 911 service in Nashville and surrounding communities. Local officials have given the public alternate phone numbers to call in case of an emergency, an indication that the system that routes all 911 calls to the appropriate local responder may have failed, Spaulding said.
For years, federal authorities had been working with state and local governments to ensure the resiliency of the 911 system, particularly in the wake of a terrorist attack or natural disaster. “It’d be nice to think we were in better shape,” Spaulding said.
Investigators are still trying to determine whether the alleged bomber, Anthony Quinn Warner, who was killed in the blast, targeted the AT&T facility. It’s not clear if Warner, who had worked as a computer consultant and was interested in technology, according to neighbors, understood that the building played an important role in the region’s communications network.
Investigators are pursuing the possibility that distrust of 5G technology and phone service generally played a role in his thinking, but they cautioned they have also gathered evidence suggesting Warner’s interest in other unusual subjects. Without a declaration of his intent, law enforcement agents are trying to piece together an understanding of his thinking from witnesses and other evidence.
Regardless of Warner’s motives, his actions have underscored how vulnerable communications infrastructure remains nearly two decades after the Sept. 11, 2001, attacks focused the attention of government officials at all levels on protecting those systems and avoiding single points of failure.
“These systems are fragile for a variety of reasons,” said Juliette Kayyem, a former senior DHS official who was involved in responses to various disasters, including the Deepwater Horizon oil spill off the Gulf Coast in 2010. For starters, facilities like the AT&T building on Second Avenue are exposed and make for easier targets, she said. Newer communications systems are often built atop older equipment, rather than scrapping everything and starting anew, which is time consuming and expensive.
Without commenting on the AT&T facility in particular, Kayyem said the decision to place critical facilities in densely populated or heavily trafficked areas is often driven by necessity, whether to be near the population being served or the public utilities like electricity and water needed to keep the facility running.
Katie O. Stone, 42, an administrative counsel with the Davidson County Sheriff’s Office who lives in the Shelby Hills neighborhood in East Nashville, said in a telephone interview that she has been without Internet service since noon on Christmas Day. After hearing news reports that most of AT&T’s service had been restored, she called on Monday to report that she and several neighbors were still without Internet service. A customer service representative attempted to reset her modem remotely, but when that didn’t work, Stone said she thought the problem had to do with the bomb on Christmas Day. She said she was taken aback when the customer service representative seemed unaware that a bomb had exploded near an AT&T transmission station in downtown Nashville.
“I really understand that there are bigger issues than living without the Internet,” Stone said. “I just don’t want us to be overlooked.”
Most states, as well as telecommunications companies, have focused in the past two decades on building fail-safe mechanisms to ensure that an entire city doesn’t lose all service in the event a key facility is taken down, experts said.
Telecommunications companies “constantly look for ways to build redundancy into the system,” Sean Joyce, a former deputy director of the FBI, said. They construct new switching networks and ways to reroute traffic when infrastructure is overwhelmed.
“But the system isn’t perfect,” Joyce said. “In certain parts of the country, resiliency will be more or less. . . . I think we have a way to go to do the best we can to ensure that resiliency.”
A spokesperson for AT&T referred to a company statement Monday that said “the majority of services have been restored in Nashville” and that “adequate power” was available on most floors of the Second Avenue building.
Less clear was why so many apparently critical systems were either in the building or may have been dependent on it.
For now, experts said officials should redouble their efforts to ensure that critical facilities are protected, particularly because of the risk of a copycat attack.
“Cities and towns need to assess their vulnerabilities in light of this attack and prepare for those eventualities,” said Thad Troy, an executive with Martin+Crumpton Group and formerly a senior official at the National Counterterrorism Center, who has worked with American cities, including Nashville, to prepare for the possibility of mass casualty attacks.
Louie Estrada in Nashville and Devlin Barrett contributed to this report.
