These coils are normally used to select slices for creating three-dimensional images, but the magnetic fields they create can also be used to exert a force on a small magnetic object inside a scanner.

So the use of military force will remain a matter largely for those willing and able to exert it.

Their trick was to shorten the lengths of the pulses of current to about a nanosecond. Rapidly changing currents exert a greater force on domain walls than do slowly changing ones.