  In their article [Phys.\ Rev.\ C {\bf 100}, 064610 (2019)], Lv, Duan, and Liu
study the enhancement of deuterium-tritium fusion reactions by the
electromagnetic field of an x-ray free-electron laser (XFEL). While we support
the general idea (which was put forward earlier in our rapid communication
[Phys.\ Rev.\ C {\bf 100}, 041601(R) (2019)]), we find that the time-averaged
potential approximation used by Lv, Duan, and Liu is not justified in this
regime and does not take into account important effects. Due to those effects,
the enhancement mechanism may actually be more efficient than predicted by Lv,
Duan, and Liu.
