North Korea doesn't have a sub with the range to get from North Korea to California and back.
It is not going home. One way trip
If you are a Nork commander, you probably don't worry about getting the crew back. And if you are a Nork sailor, the only reason you'd want to go back would be to keep your family from getting tortured to death.
If their Whiskey is still operational, it has the range for a one way trip. The old Romeos might, as well.