They had the ability to fill at least 800 warheads or 80 missiles with BW. Plus an unknown amount of bombers and aircraft equipped with spray tanks.
They had the agent, but did they have the
missiles? Every missile you load with BW is a missile not carrying nukes. And if you're planning to go silo-hunting - which the Soviets almost certainly were - you need every nuke you can get.
Also the USSR had a bioweapon program going back to the 1920s. They just were able to devote a large amount of funding plus had the means to engineer and upgrade diseases seriously starting from the late 60s. The reason is because if the US had downgraded its BW capability this would be an opportunity to score a great advantage over their sworn enemy in case of war.
The USSR was completely prepared just as much as the US if not more so to burn the world to cinders and turn the cinders into finer dust if it meant their ideological system would be the only one left standing. Of course any major exchange would pretty much wipe out any nation involved particularly the two superpowers (try telling them that.)
Why else would the Soviets by the mid 1980s have a total arsenal of 40,000 nuclear warheads, 10,000 tons of biological weapons and over 50,000 tons of chemical weapons? Because they wanted to be over prepared in case of war. The US was pretty much as bad with 25,000 warheads and 30,000 tons of CW.
This doesn't really answer the question, though: why spend all this money on BW agents instead of nuclear weapons? A nuclear weapon is more reliable, more controllable, harder to defend against, and, in aggregate, likely to do as much or more damage if you target it properly. So why make all this anthrax?
The reason this puzzles me is that I've found that, if you dig into the thinking of the time, most decisions that seem illogical from the outside make sense if you can put yourself in the decision-makers' shoes. Something like Project Plowshare (digging canals with hydrogen bombs) - in retrospect, it's a very bad idea. But if you read through the documents from the AEC, you can understand why they supported it, given the information available to them at the time, and the existing policies they had in place. Same thing with the decision to make tens of thousands of nuclear weapons, or thousands of tons of nerve agents. Not saying it was the
right decision, but it's a decision I can understand.
I just can't figure out why the Soviets spent so much money on biowarfare. I can't figure out how to make it make sense, even from the perspective of the decision-makers of the time.