ICBMs are held in mutual check by MAD.

US enjoys conventional dominance due to ability to project conventional force anywhere. This capability is in part supported by the ability to effectively shield remote force projection platforms from conventional threats. (For atomic, see MAD.)

HS conventional weapons can neutralize the defensive shields. This undermines the projection platforms. That would make US insecure. If it insists on remaining hegemon, it needs to shoot its load first. So, destablizing.

HS conventional and nuclear armed weapons look and act the same. An HS projectile coming your way gives you a short window of time to determine if it is conventional or atomic. Not a good time to toss coins. Shoot off atomic load first. Destabilizing.

That is the thesis.

I thought the main things allowing for MAD at this point were the ability of retaliatory ICBMs to launch quickly before incoming weapons destroy them, and the ability for ballistic missile submarines to survive a strike by being hidden, and thus retaliate at leisure.

I don't see how hypersonic weapons change either of that. They're not any faster than a missile, so the response time isn't worse, and they don't do anything to uncover submarines. What am I missing?

There is less critical ambiguity in the triad weapons. HS weapons introduce ambiguity in the above calculus. So with former, the global mafia could (safely) play proxy war in far flung location. Now, they can't do so, safely. All members of the global mafia cartel are concerned, since proxy wars are very good for [(settling)] business.

There's no ambiguity only because nobody has bothered to mount conventional weapons on ICBMs. There's nothing preventing that, and indeed the US has seriously considered it as a way to implement Prompt Global Strike. Those plans have been held back by the fear that launching such a weapon could be mistaken for a nuclear launch, of course.

Is the problem with hypersonic weapons just that it looks like the players won't make that same choice?

Based on the arguments in this thread -- I don't see the difference with respect to m.a.d. either.

HS launch could carry conventional or nuclear threat, it's not possible to know which after detection of launch. For mad, we must always treat these launches as nuclear -- and therefore in the end, no one uses these weapons (unless they are intending to launch global nuclear war)...?

> All members of the global mafia cartel are concerned

Who are these members?

A lot of the apparent ambiguity could be resolved by looking at the number of launches and their trajectories:

A) there are simultaneous launches against many different targets. Conventional or not, the enemy is trying to remove your ability to retaliate. The implication is clear.

B) Only a small number of weapons have been fired off at one or just a few targets. Even if the weapons inflict heavy casualties, your ability to retaliate remains intact.

There's another option as well: have enough redundancy to have substantial forces survive even a massive first strike, absorb it, and then retaliate at leisure. This seems to be the US's approach:

https://www.armscontrol.org/act/1997_11-12/pdd

I imagine other countries with smaller arsenals may not have that option. Even your B may not necessarily be an option, if their command structure relies on centralized control and would be vulnerable to a decapitation strike.

> That would make US insecure.

My earlier point about Moskits was that such weapons already exist, and have already had this effect. We just haven't admitted it yet, and almost certainly won't until we overstep ourselves and somebody sends one of our carrier strike groups to the bottom.

You think that blowing carrier battle groups out of the water wouldn't lead to a nuclear strike?

The side using these weapons hopes that US is rational and would rather lose face and backdown rather than take down the whole world with it.

So it is true, these new weapons are destabilizing.

The fact that US stumbled like a drunk into these conflicts that allowed these test cases by Russia and China to be on the table has to be one of the line items against the treasonous criminals that have been running this country for the past few decades. It did not have to be this way.

It didn't, but I think you're still underestimating the panic reaction of a country losing its major strategic assets. There is a reason that superpowers fight through proxies; we all have nuclear recourse if it goes sufficiently wrong.