Should the United States be shielding its assets military or civilian (such as aircraft and power sources) from the effects of EMP?

Electromagnetic pulse - An electromagnetic pulse (EMP), also sometimes called a transient electromagnetic disturbance, is a short burst of electromagnetic energy. Such a pulse may occur in the form of a radiated, electric or magnetic field or conducted electrical current depending on the source, and may be natural or man-made. The term "electromagnetic pulse" is commonly abbreviated to the initialism EMP. In military terminology, a nuclear warhead detonated hundreds of kilometres above the Earth's surface is known as a high-altitude electromagnetic pulse (HEMP) device. Typically the HEMP device produces the EMP as its primary damage mechanism. The nuclear device does this by producing gamma rays, which in turn are converted into EMP in the mid-stratosphere over a wide area within line of sight to the detonation.

NEMP weapons are designed to maximise such effects, especially on electronic systems, and are capable of destroying susceptible electronic equipment over a wide area. The popular media often depict such EMP effects incorrectly, causing misunderstandings among the public and even professionals, and official efforts have been made in the USA to set the record straight

Apparently any unshielded electronics, can be affected by a pulse generated of sufficient strength and at a specific altitude (say over the Western USA) and it will affect such things as electronic ignitions on vehicles, electronics on aircraft and cell phones or power stations. If it has a antenna it can be affected within the zone.