Austinjoseph asked me a valid tactical and operational question in the other thread and, after I started to type the response, it occurred to me that it is worth making a separate post on that. Here is Austin's question:
My answer is next:
Per SSBNs. For modern strategic missile submarines the ranges of their ballistic missiles are important but because those ranges are within many thousands of kilometers, it allows SSBNs to be fairly flexible in terms of choice for their patrol areas. In a specific Russian case, Soviets/Russians long ago used a system of so called bastions--well defended sea areas, such as Sea of Okhotsk--where Russian subs could operate relatively safely because the bastion was (is) within the range of Russian patrol (ASW) aviation and both nuclear and diesel-electric subs which are there to meet the main threat for Russian SSBNs--US SSNs.
Initially bastions were "built" for relatively loud Soviet SSBNs of the second generation. But those SSBNs venturing closer to American shores was nothing unusual, a bunch of them (today it is well-known), such as Kamchatka's Division's Detla IIs (pr. 667 BD) were a regular guests in the Gulf of Alaska and even closer (wink, wink). That, obviously, reduced a flight time of missiles dramatically. Once, however, modern SSBNs of pr. 955-955A (Borey-class) started to be deployed, they, being arguably the stealthiest submarines today, can operate outside bastions, but the issue is--why? Obviously, US Navy submarine force enjoys seemingly a large numerical superiority over its Russian SSN counterpart, but Russia still deploys a large number of SSKs which are perfectly suited to operate in bastion areas against the most lethal US SSNs, while both Russian patrol and interceptor aviation ensures both high operational sweep against US subs and against possible intrusion of US patrol (ASW) aviation near bastion areas. In general, modern SSBNs can launch from the pier, without leaving the base (granted they launch BEFORE base is obliterated in the first strike), or from comfortable positions near own shores, literally 20-30 nautical miles away from the bases.
So, Russian SSBNs patrol in Arctic, where Russia has an enormous experience, even American submariners use Russian terminology for Polynya (opening in the ice), while Russian SSBNs can definitely patrol somewhere in the Pacific. So, this is in short. For SSGNs the tactical and operational patterns are completely different and in a view of latest revelations about Zircon change the situation dramatically, including a possibility of strikes at continental US from both Pacific and Atlantic Oceans. As for other oceans--it makes no sense of keeping SSBN in Indian Ocean range and safety wise. Per melting, modern Russian SSBNs are extremely quiet submarines and with new subs, both SSKs and SSNs, being built for Russian Navy, the melting of the ice cap will have only secondary impact on operations of Russian SSBNs. I do not consider a possibility, in case of real conflict, of any US Navy's surface ships or CBGs surviving in Russia's littoral or near zone as a serious argument. Naval warfare changed in the last few years simply on unprecedented scale. Hope this answers your question.