The military accepted Cat. V's during Vietnam, and I had several of them in my unit. Many/most of them were not exactly intellectual giants, but they were no more likely to obey an illegal or immoral order than anyone else. Congress banned enlistment of Cat. V's a number of years ago. The people that are now being allowed to enlist are the next level above those soldiers.   BTW, by law, any Cat. IV enlistee must be a high school graduate, not that a diploma is any proof of educational attainment.