  We present a Fermi liquid approach to superconducting Kondo problems
applicable when the Kondo temperature is large compared to the superconducting
gap. To illustrate the theory, we study the current-phase relation and the
Andreev level spectrum for an Anderson impurity between two $s$-wave
superconductors. In the particle-hole symmetric Kondo limit, we find a $4\pi$
periodic Andreev spectrum. The $4\pi$ periodicity persists under a small
voltage bias which however causes an asymmetric distortion of Andreev levels.
The latter distinguishes the present $4\pi$ effect from the one in topological
Majorana junctions.
