  The long-standing question concerning Jetted Sub-Galactic Size (JSS) radio
sources is whether they will evolve into large radio galaxies, die before
escaping the host galaxy, or remain indefinitely confined to their compact
size. Our main goal is to propose a scenario that explains the relative number
of JSS radio sources and their general properties. We studied the parsec-scale
radio morphology of a complete sample of 21 objects using Very Long Baseline
Interferometry (VLBI) observations at various frequencies and analyzed the
morphological characteristics of their optical hosts. Many of these radio
sources exhibit radio morphologies consistent with transverse motions of their
bright edges and are located in dynamically disturbed galaxies. VLBI images
provide evidence for large-angle, short-period precessing jets, and the orbital
motion of the radio-loud AGN in a dual or binary system. The majority of JSS
radio sources are in systems in different stages of their merging evolution. We
propose a scenario where the rapid jet redirection, through precession or
orbital motion, prevents the jet from penetrating the interstellar medium (ISM)
sufficiently to escape the host galaxy. Most JSS radio sources remain compact
due to their occurrence in merging galaxies
