  Very recently, the Tibet-AS$\gamma$ collaboration reported the detection of
$\gamma$ rays from the galactic disk in the energy range of 100 TeV -- 1 PeV.
Remarkably, many of these $\gamma$ rays were observed apart from known very
high energy (E$>$ 100 GeV) $\gamma$-ray sources. These results are best
understood if these diffuse $\gamma$ rays: 1) were produced by a conventional
rather than an exotic (i.e. dark matter decay or annihilation) process, 2) have
a hadronic rather than a leptonic origin, 3) were produced in impulsive rather
than stable sources or, alternatively, in optically thick sources. In addition
to that, the detection of the sub-PeV diffuse $\gamma$ rays implies a limit on
the flux of neutrinos from the Galactic disk and a lower limit on the rigidity
of the cutoff in the Galactic cosmic ray spectrum.
