1. A method for detecting targets comprising moving and stationary targets with a radar system equipped with synthetic aperture radar onboard a synthetic aperture radar platform, comprising navigation equipment for accurate determination of the position of the synthetic aperture radar platform, and which is transversing a stationary ground region and targets in the said ground region, in which the synthetic aperture radar platform obtains radar data utilizing at least one antenna, the movement of the synthetic aperture radar platform during recording of the data being essentially rectilinear and uniform in an azimuth direction, and a velocity of the synthetic aperture radar platform being significantly larger than those of the moving targets, the radar system further comprising a synthetic aperture radar processor recording the radar data and the position of the at least one antenna for each transmitted radar pulse, and wherein within synthetic sub-apertures, each sub-aperture covering a surveyed region being a part of the stationary ground region, radar data are: successively merged in N iteration steps into synthetic aperture radar images of increasing resolution of the surveyed region, and wherein each iteration step comprises forming a new synthetic aperture radar image at a new iteration level by a linear combination of neighbouring successively merged synthetic aperture radar images, wherein the linear combination being obtained by a relation such that related coordinates indicates the same target position at a given reference time for all targets having a specific relative velocity with respect to the moving synthetic aperture radar platform and a specific acceleration in the direction orthogonal to the movement of the synthetic aperture radar platform, wherein m iteration steps, m<N, are performed covering the surveyed region where data from one velocity computation at each iteration level using velocity increments ΔW l of a processing velocity W, and data from one acceleration computation for acceleration increments Δÿ l are used in a motion insensitive process comprising an A-loop for producing one synthetic aperture radar-image of the stationary ground points and the targets per iteration level, wherein N−m further iteration steps are performed for a selected patch being a part of the surveyed region, each iteration step using a target detection process at each iteration level with data from at least three computations, comprising at least one velocity computation with the velocity increments ΔW l and at least one acceleration computation with the acceleration increments Δÿ l for producing one synthetic aperture radar-image per combination of velocity and acceleration computation and for detecting targets and target tracks as well as calculating target parameters R,Φ, a processing velocity W and an acceleration ÿ in a direction perpendicular to the azimuth direction, the R,Φ,ÿ,W-parameters defining an R,Φ,ÿ,W-space for each target, wherein in a target positioning process, the target position within the patch is calculated by determining the φ-parameter representing the relative velocity of the target in relation to the moving synthetic aperture radar platform, and wherein each combination of velocity and acceleration computations represents an assumption of possible target parameters.