The entire premise of nuclear détente is mutually assured destruction. Those boomer subs literally operate on the premise that they will sit at the bottom of the ocean and only come up to launch their payload at pre designated targets AFTER all the surface nukes have been deployed turning the entire world into a nuclear hell scape. Ballistic Missile Nuclear Submarines are not considered or operated as an offensive first strike weapon platform. Boomer subs rise to the surface and fire off their payload AFTER the initial hellfire has consumed the globe. Their job is to ensure that absolutely no one on the other side survives even if the Government has already been wiped out. They create a situation where "you will kill us but you die too" scenario. They are literally a massive post mortem fuck you.