since submarine has greater stealth and agility particularly comparing to land silo based liquid icbms, why not the us or other government use all the nuclear weapon arsernals replaced by sub launched missles
Agreed fully with the last two answers. Plus every time you have to replace a missile aboard a submarine then you have to bring it ashore. That is unnecessary down time and security risks for the sub.
many of the subs are in Faslane Scotland, a number of them are in Plymouth. consequently if Scotland gets independence and would not decide for nuclear subs them they'd be transferred to Plymouth. no longer precisely rocket technological know-how.
Because land based silos require less personnel to maintain and operate than a nuclear ballistic missile submarine. They are also cheaper to build. If you take out one missile silo, you take out one missile. If you sink a ballistic missile submarine, you take out 20 missiles.
Because they're easier to protect and not as easy to detect.
Contrary to popular belief that machines can last forever or very long time, it is almost impossible to find a machine that has been in continuous operation for more than 80 or 90 years, while we can find many humans that have lived that long.
