On Monday, NBC Nightly News broadcast a report claiming that White House officials had discussed using an experimental weapon to disrupt or disable a North Korean missile launch. The weapon in question, the product of the US Air Force's Counter-electronics High-powered Microwave Advanced Missile Project (CHAMP), uses bursts of microwave energy to disable electronic devices such as computers, communications and air defense radar systems.
Officials from Air Force Research Laboratory (AFRL) suggested CHAMP could be fully weaponized in a matter of weeks. But almost as a footnote, the NBC report noted that the weapon would have to pass very close to an ICBM before launch to affect it—which, despite CHAMP's classification as a non-lethal weapon, might be considered an act of war.
The Air Force has conducted tests of CHAMP, a system designed to selectively beam high-energy microwaves to cause damage to electronic systems. AFRL, Raytheon, and Boeing's Phantom Works development team tested the CHAMP concept aboard a Conventional Air Launched Cruise Missile (CALCM) in 2012 at a Utah test range. In the 2012 test, pulses from the CHAMP cruise missile disabled computers and even the video cameras monitoring them as the missile flew over them.
Raytheon and Boeing have continued development under an AFRL contract. Cecelia Fresh, a spokesperson for Raytheon, confirmed Raytheon is still the lead contractor on CHAMP. She said "Raytheon is executing on time and ahead of schedule on this contract."
CHAMP remains a research project and has not been fielded yet by the Air Force or Navy as an actual weapon—at least not yet. But the US may not be the only country developing such a weapon, since the science behind CHAMP is fairly well-known.
Researchers at Seoul National University and Yonsei University in the Republic of Korea released a paper in July documenting the effects of high-power X-band microwave beams on electronic devices, finding that "devices containing semiconductors can undergo serious failures and breakdowns due to the thermal secondary breakdown caused by the high-output transient electromagnetic waves"—in other words, the pulse can heat up some transistors in chips on a device to the point where they short out.
The researchers also theorized that "reverse voltage occurs due to the generation of surge current when caught in the PN-junction region"—the point of interface between two types of semiconductor materials. Inducing any kind of unexpected voltage in integrated circuits is not a good thing regardless of how it happens, as anyone who has had voltage induced in their network wires by a nearby lightning strike can tell you. (It's happened to me twice.)
In theory, the microwave pulses from CHAMP or a similar weapon would not harm humans or cause physical damage to vehicles and buildings. And systems properly shielded from microwaves—such as through the use of a Faraday cage or protected by reflectors—would also be unaffected by the pulses directed at them.
The problem is, in order to not harm people, the microwave pulse has to be in a "three-bears" range—it has to be just powerful enough to cause the semiconductor secondary breakdowns, but not powerful enough to cause thermal effects on humans that could cause burns or cataracts. And the range of a high-power pulse's effects are small enough that pulses need to be fired off in relatively close proximity to the targeted electronics—such as from a very low-flying cruise missile or potentially from a low-flying uncrewed aircraft.
And that's where the idea of using CHAMP against North Korean ICBMs gets dicey. If the US fired any sort of missile into North Korea, regardless of its lethality to humans, that would almost certainly be considered an act of war. The CALCM used in current configurations would, if detected by North Korean sensors, look a lot like any other cruise missile, and the sound of a turbofan flying overhead within North Korean borders just before launch systems for an ICBM failed would likely be met with the same sort of reaction as a conventional weapons strike.
In a wartime situation, targeting ballistic missiles with CHAMP-type weapons would be even more difficult. North Korea's mobile launchers could be hidden in tunnels across the country or in shielded shelters, and targeting them would require rapid collection of intelligence and prompt attack—probably not a task for a missile designed to take out electronics. But CHAMP could be used against known air defense and communication facilities and "soft" targets with some effect in support of more unconventional operations. It could also be used to knock down swarms of drones.
In a February 2016 interview with the Armed Forces Communications and Electronics Association's (AFCEA's) SIGNAL magazine, Air Force chief scientist Greg Zacharias explained:
One of the big advantages would be taking out an integrated air defense system temporarily, where you could blind them for the amount of time you might need to do an ingress without actually having to do kinetic damage to these sites... You could also go after command and control systems and anything that is dependent on the bits and bytes of adversary systems.
So, the odds of the US actually using CHAMP to fry a North Korean missile on the ground are extremely low—especially now that the news media have discussed the possibility. The announcement that discussions of doing so had happened were likely just to let North Korea know that the US has the capability to do so—to add uncertainty to future tests. The next time a launch fails, Kim Jong Un's regime will be left asking if the failure was caused by a supply chain problem or by US microwave weapons.