That's true, but it is not a highly defined network of support like some seem to think is required to commit an act of terror.ANFO is easy to make on one's own sure enough but the primary explosive used to detonate it is NOT.
In the OKC bombing McVeigh and Nichols broke into a mining company storage and stole Tovex booster and the blasting caps that were the primary.
As a matter of fact, some of the remaining stolen blasting caps were discovered on Terry Nichols KS property by the FBI.
That all came out at trial.