When I think of the use of Microwaves as a weapon, I usually think of some sort of directed beam device such as a MASER. The Air Force has recently announced development of a different military utilization of Microwaves. Instead of a beam, the device is launched inside a cruise missile and when it gets into the proximity of its target, whether it is a incoming enemy nuclear warhead or a enemy military base or ship, it emits a large burst of microwaves that can fry electronics.
One interesting possible use of this weapon is against incoming North Korean missiles. https://www.nbcnews.com/news/north-korea/microwave-weapon-could-fry-north-korean-missile-controls-say-experts-n825361
This weapon joins an technologically advanced systems including Hypersonic weapons, Directed Energy Weapons, Electro-Mechanical Pulses and satellite weapons in space. These capabilities give the US a tactical and strategic advantage over our enemies.