As long as the detonator is not with the device and the radioactive materials aren't leaking from the case, it's perfectly safe.
Until it gets stolen in transit. (FedEx loses about 0.2% of shipments annually to "employee pilferage.")
If you think that a 1 in 500 chance of someone stealing a 1-kiloton nuke the size of a softball that is only missing a detonator is perfectly safe, then you're part of the problem.
You know something? I am not connecting today. You are saying the government would use FEDEX to ship the nuke? ROFLMAO yes of course you would be 100000% correct that would be the DARWIN AWARD of the century. I figure a government shipment of a nuke is going to involve a convoy and Apache's overhead....
Just curious. Where did you get that number?