  What causes the dichotomy between very powerful and very weak radio emission
from AGNs? Perhaps the engines are the same but the jets get disrupted by dense
ISM in radio-quiet objects, or else the engines are intrinsically different
with jet power scaling with, say, black hole spin. To distinguish, one can look
for interaction between the jets and the NLR and measure the jet speed close to
the core using VLBI, before environmental effects become important. We find
that in radio-quiet AGN, the jets appear slower and have a greater tendency to
bend, and that one-sidedness and flat-spectrum cores are probably due to
obscuration.
