There are no doubt screenings to "weed out" recruits for Navy SSBNs and the Air Force's SAC/Missile Command who would be unable to launch such weapons.
BTW I don't think anyone here as ever called Crimson Tide a brilliant film around here before...
Obie: I think 'On the Beach' was a little over the top and filled with poor science. Unless you went and and hunted down evey pocket of humanity and nuked it I really doubt that human kind would be killed by a nuclear war as portraied in OTB. If you can survive (by being in fallout shelters/mine shafts/bunkers) the bombings and fallout spread by winds/storms for the first year and are willing to clean up and build new cities humanity would be back in a few centuries.
Assuming Dave Bowman donsn't just erase all the nuclear bombs before they can be used... Sorry I just read 2001 by Arthur C. Clarke few days ago.