The Draft is coming, what better way to take young skulls full of mush and completely indoctrinate them.
Would the draft be a solution if draftees refuse the jab?
More importantly, they don't want a large pool of people with combat capabilities that can be an internal threat, they already have enough issues with veterans from Iraq and Afghanistan.
They will increasingly resort to relying on mercenaries via PMCs, just like every collapsing civilization.