Our recent VLBI observations of the prominent FR II radio galaxy Cygnus A with the EVN and the VLBA reveal a pronounced two-sided jet structure .
At 5 GHz , we now have 4 epochs from 1986 , 1991 ( Carilli et al. , 1991 & 1994 ) , 1996 and 2002 from which we could derive the kinematics of the jet and counter-jet .
On the jet side and on mas scales , the jet seems to accelerate from \beta _ { app } \approx 0.1 - 0.2 ( Krichbaum et al .
1998 ) at core-separations near 1 mas to \beta _ { app } \approx 0.4 - 0.6 at r \geq 4 mas ( H _ { 0 } = 100 km s ^ { -1 } Mpc ^ { -1 } , q _ { 0 } = 0.5 ) .
For the first time we also measure significant structural variability on the counter-jet side .
For this , we derive a motion of \beta _ { app } = 0.35 \pm 0.2 at r = 9.5 mas .
The flat spectrum of the inner region of the counter-jet ( free-free absorption ) and the frequency dependence of the jet to counter-jet ratio support strong evidence for an obscuring torus in front of the counter-jet ( Krichbaum et al .
1998 ) .