The Telegraph has an opinion piece by retired Royal Navy Commander and former CO of the Ice Patrol Vessel HMS Endurance, Tom Sharpe OBE.
He feels, as I do, that we are headed for conflict over claims to Antarctica. It is after all, the last land area on earth where no nation exercises sovereignty.
China’s presence in the Antarctic is growing rapidly and, as they have shown in the South China Sea, they may choose not to accept the decisions of international courts.
Adapted from a 2021 Chinese environmental evaluation report submitted to the Secretariat of the Antarctic Treaty. Source CSIS
What this boils down to is that, after courts make their decisions, we may have to fight in Antarctic to make those decisions stick.
We don’t seem to have given much thought to the possibility of combat in and around Antarctica, but I believe it is a real possibility, perhaps not soon, but beginning in 2048 when the Antarctic Treaty comes up for renegotiation. 24 years may seem to be a long way off, but we are building now the assets that will be available in 2048.
By then the rapidly growing Chinese presence in Antarctic, as well as their Navy are likely to be in a very strong position. We are already seeing the Chinese apparently establishing dual use (civilian and military) facilities in Antarctica.
In the interim, we can expect China and perhaps others to try to skirt the rules to strengthen their presence. We need to monitor and challenge any gray zone operations.
Command Structure:
These are the Unified Combatant Commander’s Areas of Responsibility.
There is an obvious reason that Antarctica does not seem to be on anyone’s radar. Looking at who is potentially responsible for operations in the Antarctic, it is a hodgepodge. Various parts of the Continent might fall under SOUTHCOM, AFRICOM, and INDO-PACOM.
US Navy Fleet Organization
3rd Fleet, 4th Fleet, 6th Fleet, and 7th Fleet all have a nominal slice, but none of these commands consider the area their primary concern.
World map of oceans : English version. By Pinpin via Wikipedia.
There is no single national command authority that covers all of Antartica or the Southern Ocean. Really no one is in responsible for the area below 60 degrees South.
It seems likely that in the near term, Southern Ocean fisheries will require some protection. The only nation I have heard of doing fisheries protection in the Southern Ocean outside their own EEZ is New Zealand.
The Coast Guard currently operates the only US polar icebreakers. At some point the Coast Guard may become involved in fisheries protection in the Southern Ocean. If there is conflict in Antarctica, Coast Guard assets will likely be needed to gain access.
Related:
Chuck Hill's CG Blog 
Sounds like we need even more icebreakers and NSCs, possibly a larger NSC for Pacific and Antarctic duties.
We certainly need more than two icebreakers. Apparently, the Coast Guard did finally complete a new Fleet Mix Study, and it said we need nine icebreakers. Otherwise, no results have been made public.
NSC (4600 tons full load) seems to be large enough to operate well in the Pacific and the OPCs (4500 tons full load) are nearly the same size, but I do think we are going to need more large cutters, though they don’t all have to be that large.
If the icebreakers go war, they will defiantly need more robust self-defense systems.
The new Fleet Mix Study really needs to be made public.
Wonder if they considered ice capable patrol ships like the Norwegians are building?
The US Coast Guard finally got money in the budget to buy the commercial icebreaker Alviq. See “Federal budget bill includes money to buy a Coast Guard icebreaker to be based in Alaska” here: https://alaskabeacon.com/briefs/federal-budget-bill-includes-money-to-buy-a-coast-guard-icebreaker-to-be-based-in-alaska/
But the articles about buying the Alviq say, “The Coast Guard estimates that it will take six to seven years to get a purchased icebreaker fully operational for Alaska and Arctic missions,.”
Seven years to modify an existing icebreaker for the Coast Guard? That’s more time than it will take to build the Polar Security Cutter! It doesn’t take seven years to slap a coat of red paint on the Alviq, paint the USCG racing stripes, and change the flag to the Coast Guard ensign, so what are they planning to do to it that would take seven years? Adding new radars, communications gear, and other electronics won’t take seven years. Are they gong to move the helideck from the bow to the stern, perhaps? It does look like there’s room at the stern for a helideck, but that’s like redecorating or moving furniture around, unless they are planning to use the bow area to mount a deck gun, which I doubt they’re going to do.
I have to believe either the paper or Representative Sullivan misinterpreted something. It does say, “If the funding goes through, the Coast Guard estimates the icebreaker could be ready for use in 18 to 24 months.” I presume that means in commission. That would include taking possession, contracting for modification, modification, then workup, transit to homeport and commissioning.
As to the six or seven years, they might intend to do some rolling modifications with additional upgrades performed in successive yard periods, but major changes after commissioning seem unlikely.