An Electro Magnetic Pulse detonated high in the atmosphere above the central United States will end society as we know it by crippling most everything that runs on electricity in this country.
If the Chinese want to take over the USA, they don't want it to be a nuclear wasteland. What would be the point? There would be no gain. It would be a lose, lose situation because China is reliant on our abundant farm product exports and the US is one of China's biggest customers.
How would they get it done????? No hypersonic missile would be needed. A large weather balloon would work.
EMPs are not new. Their effects were well documented during nuclear tests in the the Nevada Desert and the Marshall Islands in the 1930s, 40s and 50s. Back then the Electro Magnetic Pulse effects were minimal because electronics were simple. Kitchen appliances and automobiles were unaffected. There were no cell phones. There were no computers with integrated circuits that EVERYTHING in the US runs on.
What would happen??
No electricity for days, weeks and possibly months. No phones No computers No automobiles Chaos would ensue Millions would die Civilization, as we know it, would end The Chinese would just walk in with some food and have their way with the hungry masses that remain. Americans would become the new and improved Uyghurs of Northern China.