The very public shuttering of facilities, the absence of military doctrine, etc. Yes, there could be secret congressional funding for a secret research lab serving a secret component of the military that secretly maintains readiness to do something that is strategically counterproductive and categorically denied. Do I really need to go on with how silly that line of thought is?
I really don’t understand how anyone can have such a profound level of trust in organisations that have proved themselves utterly unworthy of that trust. Have the lessons of Snowden really been forgotten this quickly??
Well that is a major mischaracterization of my views on the US government. It is funny that you mention Snowden, because many of us were called paranoid conspiracy nuts for using the exact same logic I just demonstrated to warn about dragnet surveillance programs. Watch: the USG has the disposition to spy on its citizens and the capability to do so without fear of consequences, therefor it is almost certainly happening. You can see that argument commonly popping up all over the 90s cypherpunks mailing list.
Now, try to apply that same reasoning to your allegation without looking silly. Yes, the USG has secretly run certain aspects of a public biowarfare program - and when it came to light they paid. Boom, they couldn't keep it secret and they couldn't escape the consequences (lots of very damaging legal cases and hearings). Finally, do they have an incentive? No - as I said, it makes no sense for them to reduce the cost of yet another world ending weapon. Now you could point to Russia getting caught with massive stockpiles of Anthrax after they claimed to end the program... but their nuclear program's credibility isn't comparable - they've always demonstrated clear signs of insecurity about it. That isn't the case for the USG.