In this paper we examine the relationship between control viewed as concatenation of trajectories and control viewed as interconnection of systems. We show that, for one-dimensional linear time-invariant systems, the ability to obtain a given subsystem by regular interconnection ( a prerequisite for any feedback-type structure) is equivalent to the ability to drive any trajectory into that subsystem. However, in the case of multidimensional systems, the former is a stronger property than the latter. Trajectory control lability can, however, be expressed as a regular interconnection of behaviors in an extended variable space by introducing latent or auxiliary variables. This leads as a by-product to the notion of controlling a system by means of latent variables.