Last reply, but appreciate your responses. From what I read, underwater/subsurface kill chain much more difficult of problem, comparison of it being more difficult than space. Especially compared to space-land targetting loop.

>surface ship can cover a lot of distance

Realistically we're talking about within 5000km range (not 10,000s), about 20 minute hypersonic travel, during which time a ship won't travel far. The VERY wrong lesson from carriers/surface fleet are "fast" argument is surface ships that can travel 50km per hour is fast, relative to hypersonic travelling at 10,000+. Ships obviously very slow in comparison. That actual argument is: US adversaries did not (emphasis on past tense) have the OODA loop to coordinate a fire mission rapidly, i.e. in the multiple hours it took to plan a counter mission when PRC lacked sufficient satellite coverage, carrier fleet could travel 100s of kms away. But in age of persistent, redundant ISR (i.e. PRC launching 100s of ISR satellites since, megaconstellation ISR in horizon), the ability to execute counter fire approaching immediate, and ships steaming at full speed simply can't cover meaningful distance within the 20 minutes it takes to get a mach5-10 munition downrange where course correction for account for distrance travelled is minute. Slow carriers are "fast" relative to slow brains that gives carriers lots of time to run away. But surface ships are cripplingly slow against a fast thinker with a fast trigger.

>Subsonic missiles are in theory

At 200km+ away = ~10-15 response time for subsonic, i.e. comparable to hypersonic launhced from 4000km away. But actual interception is more function of supersonic interceptor performance, slow missiles are easier to intercept. We also have a lot of reality, i.e. recent wars, subsonics (non stealth) have very, very high interception rate, like basically all of the 200+ drones and cruise from Iran vs higher % of ballistics slipping through. Both UKR and RU hitting each others subsonics regularly. I would almost argue intercepting subsonics is a solved problem. Except stealth optimized ones. I don't think those have been operational in the wild.

>want to project power

The more I think of AUKUS subs, the more I think the security aspect of AUKUS subsurface is borderline security theatre. Australia wants show (continued) commitment to US security architecture, it gets rewarded by sharing of US SSN tech, you don't really say no to that, especially if part of deal is you can recycle 100s of billions into domestic industry. Sell to public as projecting power, long endurance etc, but really US wants to known you're aligned for X decades, and continued / expanded access (pinegap, exmouth, geraldton, more airstrips in northwest AU for future USAF B21s). I don't think AU is really serious about projecting power, because IMO you really can't with handful of boats over 50 years when PRC has capacity to build 6-8 per year.

>hypersonics / subsonic

Subsonics still has place since most of US adversaries, i.e. targets they'll regularly shotting at every year (not value judgement) don't have capabilities to shoot down subsonics at scale. Syria using decades old RU anti air allegedly intercepted many US TLAMs a few years ago, but TLAMs are cheap and proven enough that weaponeers can simply afford to lob a bunch of them in calculations, so defenses eventually satuated and targets hit. IMO very different calculations once up against a modern surface vessel with lots of modern interceptors. The value proposition may change from 8B SSGN can sink multiple 500M PLAN surface combatants, to maybe 1-2 before getting sunk by ASW. Meanwhile 20-40million IRBM can sink that ship just as well (if AU piggy backs on US ISR).

In this context hypersonics I mean PRC ones - former Pac fleet deputy chief of intel Fanell confirmed PLARF launched tandem missiles from different sites a couple years ago across 2000km+ to hit moving target at sea, and later Teixeria leaks suggested they were moving at mach 8+. Meanwhile the really shit tier Iranian ballistics with bad CEP as missing barns, but huge % slipping through the densest and most advanced ABM network in the world. Indicators point to modern hypersonics can hit moving targets, while shit ballistics can penetrate modern missile defense.

IMO extrapolate both trends, and future between peer powers is fast missiles and fast interceptors at least when targetting each other's high end platforms. There is place for low mix, i.e. PRC building a cruise missile factory that can make 1000 components a day, they're absolutely doubling down on spamming cheap subsonics as well. But that's in combination of attriting away advesaries high end interceptors or used for mass mop up "economical" fires. US still uses a lot of guided bombs, cruise missiles because, bluntly it's cheap and sufficient against adversaires who can't intercept them. Meanwhile adversaries throwing 100k rockets at US hardware gets 1-2 million dollar interceptors i.e. SM6. Against PRC hypersonics that could be 3-4 20m+ SM3s for each hypersonic AShM. Subsonics will continue breaking forces that can't even deal with subsonics. Hypersonics is designed to break forces that can. Not just physically but economically... at some point spending 100s of billions to procure platforms vs hypersonics maybe unwise. IMO one big value of hyperosnics is asymmetrical disruptiveness against legacy force compositions, the 5 carriers parked outside Persian Gulf to stomp Iraq, might not get within 4000km of PRC coast... where none of the carrier aviation has range + tanking + standoff to deliver more than a few munitions to PRC targets. It's like pulling a sniper rifle from your quiver of arrows, and watch everyone change behaviour in response.