In this paper, we study method for identification of targets in a cluttered environment using the inter-element response, the response matrix, of an active array. We examine the properties of the response matrix and its singular value decomposition (SVD). In particular we analyze the patterns of singular values for scatterers of different sizes and use it for detection and characterization of scatterers. We use the corresponding singular vectors to image the scatterer and present a novel approach using the SVD of the response matrix for imaging the shape of extended targets. We form the difference matrix between response matrices measured at two different times and use its SVD to detect significant changes in a cluttered medium. We also demonstrate that by measuring the response matrix at consecutive times we can track the motion of a target in a cluttered environment. Numerical experiments are presented to illustrate and validate our approach.