Just did a search and couldn't find anything current on it. I would imagine it's for many varied missions.
Alright then different question, what is the point of having 100+ B-21s?
Supposedly the B-21 will have roughly half the payload of the B-2 but other than that is supposedly about the same (same slow 600 or thereabouts topspeed, but ultralong range and low radar visibility). So it’s a slow but sneaky bomber with long range but a relatively small payload. We obviously need a few of those for first strike type of options but I’m not sure of their value in taking on low grade third world targets.
The reason I say why do we need them is around the same time, no more than 2-5 years after the B-21s are in large numbers, we’re supposed to officially have large numbers of SR-72s/Auroras. Unlike the SR-71s which they denied as having a nuclear component for most of its life, the Pentagon is blatantly saying the SR-72 isn’t just a spy plane but a nuclear bomber. And the SR-72s conservatively will go Mach 6 (4,603 mph) with their scramjets, maybe even up to Mach 11 (8,439 mph) if the tinfoiler scientists are correct.
So if we’re going to publicly have a bunch of ultrafast, incredibly high (basically space), bombers that are essentially unstoppable until very long range and powerful lasers are deployed by the Russians and/or Chinese to perform the “first strike” nuclear deterrence, what’s the point of having a ton of low and slow stealthy ones? Some I get, you don’t want to assume the scramjet bomber is unstoppable because at some point chemical lasers will be viable of a strength to MAYBE knock down something they can see (Btw I don’t think we’re anywhere near that, probably 30-40 years, the US barely has lasers that can hit stationary targets from upclose currently in the public sphere). So I get the not all eggs in one basket, but it seems to me that 20-40 of them would be sufficient as a supplement to the SR-72s. (Plus this ignores the other spaceplanes we will/currently have probably that capable of deploying mass driver weapons that would have the destructiveness of a small nuke but no fallout).
So I still see a role for the B-52s, we need a platform that’s cheap and can drop tons of bombs on low tech opponents. I see the need for the hypersonic scramjet bombers with low payload but able to deliver one or two nukes in a currently unstoppable format for first strike. I see the continuing role for a FEW B-2s and B-21s for the alternative backup plan IF the enemy develops a way to counter the hypersonic craft. But I don’t see the need for 120+ of the B-21s.
(Sidenote, I am aware that the Pentagon is claiming the B-21s will also be useful as a kind of quasi AWACS station directing a huge swarm of drones around it, but they also claim that’s what the F-35 is going to do as a secondary role as well. And even if you believe that the future will be swarms of small drones using short distance lasers for defense and armed with bombs (even nukes) as suicidal offensive weapons, do we need 120+ of them?)