Exactly…
Once the delivery was purely on 20 liquid fueled DF-5/5A. DF-31 (which is single warhead) can only reach a tiny part of the CONUS.
…

From memory, those 20 DF-5/5A(mounted in silos) are considered “first strike” weapons. Armed and ready to go. The reasoning behind the tiny numbers is to prevent an accidental launch. The rest of the retaliatory force of DF-5/5A are stationed in horizontal tunnels dug in the central mountain ranges. The number of these DF-5/5A is unknown, but probably at least 100 (armed with either 3MT or 5MT warheads).

DF-5 is same as CSS-4