A reasonably small nuke detonated in orbit somewhere over the heartland knocks out anything not in a Faraday cage here in the US.
“Since the Cold War, Russia has experimented with the design and effects of EMP bombs. More recently, the country has performed several cyber attacks on the United States, which some analysts believe suggests possible future nationwide blackouts caused by super-EMPs, since Russia is known to possess them. Along with ordinary warheads equipped with Super-EMP capabilities, Russia has been developing hypersonic missiles that, in 2021, are far more difficult for U.S. defenses in the form of radars and satellites to detect in a timely manner. This method makes the act of nuclear deterrence, which is a key strategy for the United States in preventing nuclear war, nearly impossible.[43]
Plans of a device that is capable of placing a nuclear weapon into space were first introduced by the Soviet Union in 1962 when they developed a system, known as Fractional Orbital Bombardment System, to deliver nuclear weapons from above the Earth’s atmosphere.[43] Compared to super-EMPs that target ground operations, proposals have been made by Russia to develop satellites supplied with similar EMP capabilities. This would call for detonations up to 100 kilometres (62 miles) above the Earth’s surface, with the potential to disrupt the electronic systems of U.S. satellites suspended in orbit around the planet, many of which are vital for deterrence and alerting the country of possible incoming missiles.[41]”
Tube equipment will likely survive but semiconductor stuff not Faraday caged... fried beyond repair. All computers. All cell phones. 99.99% of the communication infrastructure. Toast.
You do realize that there are engineers and scientists that dispute that 99.99% of electronics will be fried beyond repair?
How do “cyber attacks” (of the sort Russia has tried, with limited success) “suggest possible future nationwide blackouts caused by super-EMPs”? The two processes are nothing alike, other than intent, and even that is considerably different, as the cyber attack does little to no physical damage to computer equipment itself.
Scientists can be whacky (esp. when hawking research $$) but most engineers know their stuff, at least within their specialties. Otherwise (for example) you would not be reading this.