Abstract. Let M" be a compact C°° manifold, n > 4, admitting a vector field with every orbit a circle. Then there exists a completely controllable set S consisting of two nonsingular C°° vectors X and Y such that every orbit of A-is a circle.An autonomous control system on a smooth manifold M is the same as a set of vector fields on M. A set S of vector fields on a smooth manifold M is said to be controllable if for every pair (m, m') of points of M there exists a trajectory of S from m to m'. Here a trajectory of S is a curve which is an integral curve (orbit) of some X G S or a finite concatenation of such curves such that a trajectory of S run in reverse is not allowed. (We refer the readers to [2] for details.)In [2], N. Levitt and H. J. Sussmann showed that on every connected paracompact manifold of class Ck, 2 < k < oo, or k = w, there exists a completely controllable set S consisting of two vector fields of class Ck~x.For simplicity, we assume that all the manifolds, vector fields, etc., considered here are of class C°°.A manifold M is called closed if it is compact and without boundary. Let Dk denote the A>dimensional disk and Sk~x its boundary.The purpose of this paper is to prove the following theorem:Theorem. // a connected closed n-dimensional manifold M", n > 4, admits a vector field X0 with every orbit a (nondegenerate) circle, then there exists a completely controllable set S consisting of two nonsingular vectors X and Y such that every orbit of X is a circle and Y has finitely many closed orbits.We first give a brief sketch of the proof. Key words and phrases. Completely controllable set of vector fields, orbits, trajectory, round handle decomposition of a manifold.'Supported by the University of Kansas General Research Fund.