Probes of Jet-Disk-Coupling in AGN from Combined VLBI and X-Ray Observations

The formation of powerful extragalactic jets is not well understood at present as well as the associated key question:``What makes an AGN radio loud?‘’. Here we discuss how the combination of VLBI and X-ray spectroscopic observations allows the inter-relation between the accretion flow and the formation of relativistic jets in AGN to be explored.