(CNN) — Domestic violent extremists have in the last year increasingly shared tactics with each other on using guns to attack electric power stations in a move that likely escalates the threat to US critical infrastructure, according to a Department of Homeland Security bulletin obtained by CNN.
Following multiple high-profile attacks on US power substations last year, extremists have stepped up sharing of "online messaging and operational guidance promoting attacks against this sector," says the DHS bulletin, which was distributed to US critical infrastructure operators on Monday.
The information and tactics shared by extremists online include "detailed diagrams, simplified tips for enhancing operational security, and procedures for disabling key components of substations and transformers," DHS warned.
The last year saw a flurry of physical attacks and vandalism on US electric infrastructure.
Tens of thousands of people lost power in Moore County, North Carolina, in December after Duke Energy substations were damaged by gunfire. On Christmas, thousands of people lost power in a Washington county after someone vandalized multiple substations there.
A DHS spokesperson told CNN in a statement: "The Department of Homeland Security regularly shares information regarding the heightened threat environment with federal, state, local, tribal, and territorial officials to ensure the safety and security of all communities across the country."
Some of the threats to electric infrastructure have come from people espousing racially or ethnically motivated extremist ideology "to create civil disorder and inspire further violence," the FBI previously said in a November bulletin sent to private industry.
In the months since the FBI analysis, concerns from the federal officials about the threat appear to have grown more acute.
In the intelligence bulletin distributed Monday, DHS officials expressed concern that gun attacks "could become more appealing and spread to other infrastructure sectors" because they are a "low-risk" and "high-reward opportunity" and because attacks on the electric sector can impact other sectors.
Major US electric utilities routinely drill for such attacks, and the uptick in activity over the last year has only heightened the vigilance in the sector.
"Electric utilities have always taken substation security seriously, primarily because of safety," said Patrick C. Miller, the CEO of Oregon-based Ampere Industrial Security, which works with utilities to boost their security.
"What hasn't been considered as much, until recently, has been firearms, ballistics, drones and other threats from outside of the substation fence," Miller told CNN, adding that it "takes some planning and investment to move to a more secure posture."
"That is definitely happening but doing this across the spectrum of different facilities takes time and the highest risk situations should always come first," he said.
The-CNN-Wire
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