The article provides a comparative analysis of short-range and nonlinear radar with a view to further modernization of inspection and surveillance complexes, depending on the signs of demasking of objects subject to customs control. In this regard, using the proven methods of near-surface (subsurface) and nonlinear radar to detect and evaluate the parameters of objects, the author considers the possibility of implementing customs express control for monitoring railway transport with large-sized objects made of optically opaque materials, including contraband radio equipment. To detect possible demasking features of objects and make final decisions, a correlation method with the maximum likelihood of information signals from, as a rule, spatially distributed targets with demasking features is proposed. At the same time, the effectiveness of the detection and evaluation of information signals and the subsequent classification of demasking features of objects usually depends on the effective backscattering surface of the objects of study. The presence of a control arsenal of the latter, experimentally obtained in an anechoic chamber, similar to fingerprinting, significantly speeds up the procedure for recognizing the demasking features of objects. The required effective surface of the receiving antenna and the imaginary effective surface of the anechoic chamber should not exceed a certain predefined value, since the measurement error will be smaller, the lower the background signal level.