Pete Comment

I think it is rare that a US SSBN is reported visiting an Indian Ocean port, particularly to occasionally controversial Diego Garcia. Also note, in the Report  below, USS West Virginia is home based in the Atlantic (not Pacific) specifically at Kings Bay, Georgia. 

This publicized Indian Ocean presence may be partly for Putin's benefit, reminding him that however much he nuclear sabre-rattles, he is surrounded by US SLBMs. This includes central Russia's 31st and 33rd Rocket Army ICBM heartland.

I assume from Kings Bay this SSBN rounded the Cape of Good Hope (Southern Africa) to get into the Indian Ocean. Or perhaps it took the longer way round - around Cape Horn and then around "Australia's" Southern Ocean into the Indian Ocean (certainly not through the narrows of the Indonesian archipelago). 

This is also assuming this SSBN does not attempt Arctic Ocean sea-routes that are presumably over-frequented by Russian SSNs and other Russian ASW platforms. 

Once Australia's navy has its own SSNs one major role may be contributing to the defence of US and UK SSBNs. This would more directly involve Australia's navy in the US and UK(?) extended nuclear deterrent that covers Australia. Perhaps that has been put into words in a secret part of the AUKUS agreement. SSNs from Australia's main submarine Fleet Base West (near Perth) 2040s onwards, may be well situated to intercept China's increasingly frequent SSNs and even SSBNs entering and leaving the Indian Ocean.

Australia's Fleet Base West may increasingly serve as a more comfortable (also a   duplicate) Indian Ocean base for US nuclear sub visits, especially for crew changeovers. 

Report 

 US DoD’s unified Strategic Command, November 28, 2022, reports:

"USS West Virginia visits Diego Garcia during extended deterrence patrol

By U.S. Strategic Command Public Affairs

DIEGO GARCIA, British Indian Ocean Territory

 - The Ohio-class ballistic missile   submarine USS West Virginia (SSBN 736) stopped in Diego Garcia for a brief port visit Oct. 25-31, 2022, during an extended deterrence patrol providing security and stability to our Allies.

The visit, part of West Virginia's sustained deterrence operations in the United States Central Command and Indo-Pacific Command areas of responsibility, emphasizes the unmatched capabilities of a ballistic missile submarine to deter and, if necessary, respond from anywhere on the globe.

"Every operational plan rests on the assumption that nuclear deterrence is holding, and SSBNs like West Virginia are vital to a credible nuclear deterrence for the United States and our Allies,"said Adm. Charles Richard, commander of U.S. Strategic Command.

West Virginia is one of 14 Ohio-class SSBNs that make up the most survivable leg of the nuclear triad by serving as an undetectable launch platform for submarine-launched ballistic missiles. Before visiting Diego Garcia, West Virginia surfaced to embark Gen. Michael Kurilla, the commander of U.S. Central Command, in the Arabian Sea and participated in a joint, U.S. Strategic Command-directed communications exercise to validate emerging and innovative tactics in the Indian Ocean.

"West Virginia, like each of our ballistic missile submarines, is specifically designed for extended deterrent patrols," said Vice Adm. William Houston, commander of Naval Submarine Forces. "The stealth and response capability of these submarines combined with the crew's training make our SSBNs the most powerful warships in the world."

The submarine also conducted a complete crew exchange in Diego Garcia and a subsequent replenishment at sea, highlighting the SSBN force's readiness and flexibility to remain on patrol for an extended period of time.

West Virginia is one of six ballistic-missile submarines stationed at Naval Submarine Base Kings Bay, Georgia, and can carry up to 20 submarine-launched ballistic missiles with multiple warheads.

Submarine Forces execute the Department of the Navy's strategic deterrence mission in and from the undersea domain. In addition to lending added capacity to naval forces, Submarine Forces, in particular, are expected to leverage those unique advantages that come with undersea concealment to permit operational, deterrent, and combat effects that the Navy and the nation could not otherwise achieve.

U.S. Strategic Command forces operate around the world, around the clock, to deter strategic attacks and employ forces as directed to guarantee the security of our Nation and our Allies. For more information about U.S. Strategic Command, visit https://www.stratcom.mil/. "

USS West Virginia (SSBN 736) docking at Diego Garcia. See the very short official Stratcom Youtube of the visit.
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