  We report the first detection of non-thermal broadening of OVII lines in the
warm-hot $\approx 10^6$ K circumgalactic medium (CGM) of the Milky Way. We use
$z$=0 absorption of OVII K$\alpha$, OVII K$\beta$, and OVIII K$\alpha$ lines in
archival grating data of $b>$15$^\circ$ quasar sightlines from $Chandra$ and
$XMM$-$Newton$. Non-thermal line broadening is evident in two-third of the
sightlines considered, and on average is constrained at 4.6$\sigma$
significance. Non-thermal line broadening dominates over thermal broadening. We
extensively test whether the appearance of non-thermal line broadening could
instead be because of multiple thermally broadened velocity components and
robustly rule it out. Non-thermal line broadening is more evident toward
sightlines at lower galactic latitude indicating the Galactic disk origin of
the nonthermal sources. There is weak/no correlation between non-thermal line
broadening and the angular separation of sightlines from the Galactic center,
indicating that the nuclear region might not be a major source of non-thermal
factors.
