  X-ray emission from the gravitational wave transient GW170817 is well
described as non-thermal afterglow radiation produced by a structured
relativistic jet viewed off-axis. We show that the X-ray counterpart continues
to be detected at 3.3 years after the merger. Such long-lasting signal is not a
prediction of the earlier jet models characterized by a narrow jet core and a
viewing angle of about 20 deg, and is spurring a renewed interest in the origin
of the X-ray emission. We present a comprehensive analysis of the X-ray dataset
aimed at clarifying existing discrepancies in the literature, and in particular
the presence of an X-ray rebrightening at late times. Our analysis does not
find evidence for an increase in the X-ray flux, but confirms a growing tension
between the observations and the jet model. Further observations at radio and
X-ray wavelengths would be critical to break the degeneracy between models.
