The attacks against two power substations serving Moore County, N.C., on Dec. 3 has rightly triggered new concerns of behemoth proportion about security for this nation’s power grid.

But the Dec. 3 incidents also should resurface deep concern about how an electromagnetic pulse could inflict devastation in the United States — even more so than the kind of attack that immediately portended an extended period without full restoration of power for the North Carolina county just northwest of Fayetteville and Fort Bragg.

For many state and national governmental officials, the Moore County outage, perpetrated by gunfire from a person or persons described by the county’s sheriff as someone who “knew exactly what they were doing,” revived fears emanating from a similar attack in 2013 south of San Jose, Calif.

Those responsible for that sniper attack against a Pacific Gas and Electric Co. transmission substation still have not been apprehended, and with each passing month, it seems less likely they ever will be found and charged.

Meanwhile, a Dec. 4 article written by Bridget Johnson, managing editor for the publication Homeland Security Today, said “recent extremist materials have discussed and encouraged targeting critical infrastructure including cellphone towers, railways, the agriculture sector and more — but the greatest share of these public-facing infrastructure threats focuses on the power grid.”

When she wrote that article, Johnson only could speculate about the possibility that the Dec. 3 attacks were inflicted by domestic terrorists/extremists. However, a sobering point she brought up in that article was a 261-page handbook released by people she described as accelerationists — a handbook containing at least 45 pages dealing with attack threats, tips or encouragement directed at critical infrastructure sectors.

Her observation that “a determined adversary with insider knowledge as to what to shoot, and how to cripple components, is difficult to stop” should make Americans worry.

Last January, according to Johnson, who also is a terrorism analyst and security consultant, a Department of Homeland Security memo warned that domestic violent extremists including white supremacists and accelerationists were continuing “to aspire to attack the power grid utilizing encrypted messaging platforms and simple tactics that could make a plot harder to detect in the planning stages.”

Regarding the electromagnetic pulse threat, the United States learned much from its 1962 explosion of a nuclear weapon high above an atoll in the Pacific Ocean.

Worries of a similar nature should abound from the unconscionable Dec. 3 attacks and the daunting possibilities that they represent.