Today, it is impossible to imagine that any part of the country's infrastructure operates without electronic equipment based on microprocessors and computers. This is especially true for critical systems such as power supply, water supply and sewage, communication and transportation networks. Modern electronic equipment uses lower level electrical signals, (compared to electrically powered equipment that was used in the beginning of the previous century or even electronic equipment of the previous generation that was based on electron vacuum tubes) and features much more difficult and branched internal architecture. This was the key for the sharp increase of modern electronic equipment's susceptibility to HighAltitude Electromagnetic Pulse (HEMP), and that of the entire country's infrastructure. What is the actual susceptibility of different electronic elements and devices that employ them to HEMP? How can we use this knowledge in practice? This article deals with the answers to these questions.