  Recently, very high-energy photons above 100 GeV were reported to be detected
from GRB~190114C and GRB~180720B at, respectively, 100-1000 s and 10 hours
after the burst. We model the available broad-band data of both GRBs with the
synchrotron plus synchrotron self-Compton (SSC) emission of the afterglow
shocks. We find that the sub-TeV emission of GRB~180720B can be interpreted as
the SSC emission from afterglow shocks expanding in a constant density
circum-burst medium. The SSC emission of GRB~190114C dominates over the
synchrotron component from GeV energies at $\sim100$ s, which can explain the
possible hard spectrum of the GeV emission at this time. The extrapolated flux
of this SSC component to sub-TeV energies can explain the high-significance
detection of GRB~190114C by the MAGIC telescope. The parameter values (such as
the circum-burst density and shock microphysical parameters) in the modeling
are not unusual for both GRBs, implying that the detection of sub-TeV photons
from these two bursts should be attributed to their large burst energies and
low redshifts.
