[the_duke]

A LEO sat at 300 km altitude does a full orbit every ~90 minutes.

Put a few hundred missiles in orbit, give them enough spare fuel to travel a decent distance on their own, and you have a pretty substantial worldwide strike capability.

[laverya]

Do you know what the difference is between an ICBM and a warhead predeployed in orbit?

The ICBM can hit anywhere (instead of just where the orbit track happens to pass), in less time (or at most the same time, since deorbiting takes around half an orbit) with a better mass fraction (since it doesn't have to reach orbit and then deorbit afterwards) while being more accurate (you know exactly where the launch platform is, while satellites are harder to locate) and less vulnerable (you can harden an ICBM silo far more effectively than a satellite).

Really, it's hard to think of something that satellite anti-ground weaponry does better.

[rocqua]

Detection?

There is a lot of icbm detection. Unplanned rocket launches could lead to global nuclear annihilation. What happens if something seems to deorbit above the US? How much early warning and procedure is there?

Especially if you want to deliver conventional munitions to a non-nuclear power, a system like this seems better than an ICBM.

[laverya]

Except that detectability is an advantage, in the doesn't-set-off-global-thermonuclear-war sense. If your nuclear (or command) assets can be removed at any time without enough warning to launch, that means you have to launch now before that happens.

If you want to hit something with a conventional warhead in a non-peer state without warning, why not use a stealthy cruise missile instead?

[rocqua]

Stealthy cruise missles need a much longer time than anything from space.

I am not advocating weapons in space btw. Just pointing out what the advantages are.

[nradov]

What's the point of that when you can have an even more substantial worldwide strike capability at far lower cost with ground-based missiles.

[catillac]

This handwaves a lot of stuff. The least of which is that with the way satellites orbit, even though they orbit in 90, they’re not over the same ground track again for like 12 days. It’s not the case that a weapon used satellite would have a firing solution every 90 minutes.

[treeman79]

Meanwhile opponent straps nuclear hand grenadines to a few thousand drones and flies them to your bases. At a fraction of the cost.

[hungryforcodes]

And they are not doing that now, because...

[iso1210]

Smallest nuclear bomb (not dirty bomb) made was 23kg, literally suitcase size. However if you have one and want to use it, you're probably better off sending it in on a shipping container or truck (or commercial or private plane)

[treeman79]

Lots of detectors for those. Not sure how extensive, but it’s a known attack vector.

Apparently it’s hard to fully shield weapons grade material