NK doesn't require a ballistic platform to reach the US. They have the largest submarine fleet in the world.
Don't think for a moment that Iran has something that NK doesn't have, or vice-versa.
FYI
August 15, 2004 4:45 PM
Iran says missiles can hit anywhere in Israel
By Paul Hughes
TEHRAN (Reuters) - A senior Iranian military official has said Israel and the United States would not dare attack Iran since it could
strike back anywhere in Israel with its latest missiles, news agencies have reported.
http://www.swissinfo.org/sen/Swissinfo.html?siteSect=143&sid=5146411
NK bought some old Soviet era ballistic missile boats supposedly for scrap a few years back. I believe they were Golf class boats. They could be modified and made operational if they werent too far gone, but I wouldnt sail in one-too old and too much hull stress.
Sail mounted vertical launch tubes capable of firing the SS-N-5 or SS-N-6 missile, IIRC