A method is disclosed wherein engineered particles are used as obscurants and taggants for vehicles. In some embodiments, the engineered particles are nano-crystals or micro-spheres (doped or un-doped). In some embodiments, the particles are engineered to re-radiate the energy that they receive at either the same wavelength or a different wavelength than that of the incident photons. Particles that scatter light at the same wavelength as the interrogating beam are advantageously used as taggants. Particles that scatter light at a different wavelength as the interrogating beam are advantageously used as obscurants. In some embodiments, the method comprises storing a quantity of particles in a first vehicle, and releasing a portion of the particles in an ambient environment of the first vehicle.