The US military is hard at work designing, building, and using directed energy weapons (HERFs -- high energy radio frequency or microwave weapons) for use against micro-electronics and fuel vapor. Unfortunately, directed energy weapons are much more valuable to global guerrillas than nation-state militaries due to the target imbalance between nation-states and non-state foes. The technology needed to build these weapons is generally available and inexpensive (numerous experiments, including this one, scroll to bottom, with a converted microwave oven demonstrate this). Homemade directed energy weapons will eventually become the weapon of choice for global guerrillas intent on infrastructure destruction.

A good reference on this is Col. Eileen Walling's "High Power Microwaves: Strategic and Operational Imperatives for Warfare" (PDF). She lists four distinctive characteristics of a microwave weapon:



They don't rely on knowledge of the system.



They leave persistant and lasting effects on the system through destruction of circuits and components.



They can impact systems even when they are turned off.



To counter the weapon the entire system must be hardened.

Entry to a system can be direct or indirect (through a variety of backdoor channels).



Destruction occurs from the inside out.



Extreme lethality for electronic components (and fuel systems).



Repair is extremely difficult -- it requires high level systems analysis.



Most systems are not hardened against microwave frequencies.



Area attacks are possible.



Insensitive to weather (rain, fog, etc.).



Long reach depending on power used.



Replenishment is easy (nothing except power is expended).



Scalable size (a weapon that weighs less than 10 lbs is possible).



Logistics are limited to battery/power source replacement.



Limited collateral damage.

Here are some attributes of a microwave weapons: