The FDA regulates the drug industry, not the DEA, but thanks for playing.
The DEA arrests drug dealers.
I believe my point to be still valid, even without mention of the FDA, although if FDA can enforce its regulations, that may make the DEA unnecessary. Since the nature of illegal drug trade is quite violent, however, removing enforcement to a separate agency was likely deemed necessary when DEA legislation was drafted. Inspecting a research or production facility is rather different and less violent than pursuing crack distributors.