A method of deactivating land mines buried in ground comprises projecting high-pressure water jets into ground, cutting through ground with the high-pressure water jets, and making at least one cut through a land mine or cutting through at least one land mine that had been under the ground, the cutting of the land mine reducing the performance of the land mine. The method may reduce the performance of the land mine by rendering the land mine inactive to normal detonation procedures for the land mine. To reach as many surface areas on the buried landmines, it is preferable that at least two high-pressure water jets are spaced apart are used to cut through the ground. The method may be practiced with the high-pressure water jet being carried on a vehicle and cutting is done in a line that is formed at least in part by movement of the vehicle over the ground while the high-pressure water jet is cutting ground. An apparatus for the reduction in effectiveness of land mines buried in ground may comprise a self-contained push-cart unit or a unit attached or attachable to a vehicle. A complete system could comprise a vehicle having a source of liquid, a high-pressure pump to move the liquid under high pressure, a nozzle directing a liquid jet path for the liquid, a support for the nozzle, abrasive delivery system, and nozzle being controllable to direct the liquid towards the ground while the nozzle is fixed relative to the vehicle.