The concept of driven magnetic reconnection is examined in the framework of linear theory. An imposed small-amplitude magnetohydrodynamics (MHD) plasma flow velocity is specified at a finite distance from the magnetic neutral line in a plasma current sheet. The critical condition for driven reconnection is shown to be a function of the wavelength of the imposed flow compared with its distance from the neutral line as well as the orientation of the incoming plasma flow. Two-dimensional, incompressible MHD is used to develop the theory, and a simple model for the collisionless reconnection problem is analyzed for the linear, driven reconnection growth rate. According to the theory, the time scale of the delay of the substorm energization is of the order of a half an hour. Other relevant evaluations of geomagnetic tail quantities are obtained. ¿ American Geophysical Union 1988