Chemical and biological weapons require a significant research/development/manufacturing infrastructure.
OK, I'll be more specific: Even I could make chemical and biological weapons. Fifty million people, who are very determined to inflict harm on US citizens, can do the same. Perhaps you prefer to underestimate enemies?
Two hundred pounds of glassware, a house-hold heating/air-conditioner system, some pumps, and some compressors does not constitute "significant infrastructure". All of this stuff is dirt cheap and easily available.
"The research personnel come from where?", you might ask. They are trained right here in our own schools. Books can be found all over the internet and in every bookstore.
I think you don't grasp how easy it is to manufacture these weapons .... much easier than conventional arms. If this were not the case, why ground the crop dusters?