The Tactical High-power Operational Responder (THOR) is a high-power microwave directed energy weapon developed by the United State Air Force Research Laboratory (AFRL).
THOR is designed to counter unmanned aerial vehicles (UAVs) by sending out a high-power, short pulse of microwaves to disable electronics through overwhelming critical components intended to carry electrical currents. This is effective at intercepting drone swarms; while a laser needs time to burn through one at a time, an HPM can fire in an arc to disable multiple at once and refire in rapid succession. Compared to hard-kill methods for engaging drones, THOR's radio bursts have a wider engagement range, are silent, and are instantaneous. Intended for base defense, the system resembles a 20 ft (6.1 m) shipping container with a satellite dish attached. It can be transported on a C-130 Hercules and assembled by two personnel in under three hours.[1][2][3][4][5]
THOR first began testing in spring 2019. The system was developed quickly in 18 months for $18 million. The program represents a collaboration between AFRL, BAE Systems, Leidos, and Verus Research, an engineering firm based in Albuquerque.[6][7][8] An Air Force official said in December 2020 that THOR was being tested "in a real-world setting" in Africa,[9] but that statement was then retracted.[10]
The AFRL began solicitations for contractors to develop a follow-on prototype to THOR in July 2021 called Mjölnir, named after Thor's hammer to keep the new system's name in the family. Mjölnir will incorporate improvements in capability, reliability, and manufacturing readiness to produce a deployable system that can be made in large numbers. In February 2022, the AFRL awarded Leidos a $26 million contract to build the system.[4][11]
On 5 April 2023, THOR successfully engaged multiple targets in a simulated swarm attack in a demonstration at the Chestnut Test Site, Kirtland Air Force Base; the number of drones downed and at what range was not disclosed.[7][8][12][13]