US ICBMs been inertially guided for decades. They predate GPS. Once launched, they have no radio inputs.
Some weapons do use GPS. The Joint Direct Attack Munition, the US's most common "smart bomb", is GPS-dependent. There's an inertial backup, but it's not that good. With GPS, it can hit a bunker or an artillery emplacement or a parked vehicle. Without GPS, small targets are out.
DARPA has been working on small, low-cost inertial systems with enough accuracy to remove GPS dependence. Exactly how good those systems are and which weapons systems now use them is not talked about much. Here's the project poster.[1] This is an improved form of MEMS accelerometers and gyros, not new physics. DARPA has a project for that, too, but the near term goal is small, cheap, and disposable for munitions.
There's much current interest in weapons which combine gun, bomb, and missile technology to boost range. Bombs with a small jet engine and wings for extra range exist. Both the US and Russia have them. Artillery rounds with a rocket upper stage are becoming available. The general idea is to have stuff you can shoot into heavily defended territory.[2]
Is this the one technology used by Russia to bomb Ukraine. As it is so cheap the missile defend system is useless as it is just too expensive to fight it. The f16 is starting to prevent the airplane that throw the bomb with some gps guidance system.
> US ICBMs been inertially guided for decades. They predate GPS. Once launched, they have no radio inputs.
That's how the original Third Reich V-rockets worked as well, and they were shockingly inaccurate. It didn't matter for the Nazis, as their intention was to spread terror among the British population instead of actually hitting specific military targets, but in a modern war waged under the rules of war, "collateral damage" can actually be a war crime, and even if not, it will provoke significant opposition.
This can at the moment be seen in Ukraine, where Ukraine regularly (and rightfully, IMHO) claims that Russia's strikes violate the rules of war by hitting civilian infrastructure en masse, and where Ukraine's strike capability against Russia is severely impeded by Russian GPS jamming (that also causes serious safety issues for civilian airlines [1]), but also in the current Israel/Palestine war, where Hamas regularly claims that Israeli strikes are too imprecise [2] or unguided [3], while Israel claims it hits hidden weapons caches that subsequently explode and cause a lot of secondary damage [4].
While the V2 made use of a key element of inertial navigation systems (the Pendulous Integrating Gyroscopic Accelerometer [1]), it was apparently only used to cut off the motor when the desired velocity was reached (the other elements of the control system guided it on a trajectory which curved from vertical to 74 degrees as a function of time, with the azimuth determined by the positioning of the rocket on its launch stand prior to firing.) Consequently, the performance of modern inertial navigation cannot be deduced from V2 accuracy (or, rather, the lack thereof.)
ICBM is likely to deliver a nuke. Which will probably take out a 20 km radius circular area. It is not going to be used to target a base with 100 soldiers.
It is if the goal is to deter without launching a city roast fest. That’s one possible step to e.g. answer a first limited strike without starting a disastrous exchange. And US nukes can be set to low yield.
If NATO ever has any intention of deterrence through detonating a nuke, it will be done in exactly the way it's been specifically planned and openly explained: France has a specific nuclear policy, one of the only ones, that allows them to use nukes before an adversary does. They have a specific nuclear missile fired by plane that will be used as essentially a giant warning shot.
Nobody would fire a warning shot using an ICBM, because if things are hot enough to require a warning shot, that leaves a whole lot of interpretation up to your adversary who is quite likely to respond with their own ICBMs, before finding out yours were loaded with conventional munitions to make a point.
There are however, shorter range ballistic missiles, Russia has a lot of them (the US mostly gave up mid range ballistic missiles in a nuclear treaty) and has even launched a few with concrete "nuclear warhead simulation masses" at Ukraine.
Some weapons do use GPS. The Joint Direct Attack Munition, the US's most common "smart bomb", is GPS-dependent. There's an inertial backup, but it's not that good. With GPS, it can hit a bunker or an artillery emplacement or a parked vehicle. Without GPS, small targets are out.
DARPA has been working on small, low-cost inertial systems with enough accuracy to remove GPS dependence. Exactly how good those systems are and which weapons systems now use them is not talked about much. Here's the project poster.[1] This is an improved form of MEMS accelerometers and gyros, not new physics. DARPA has a project for that, too, but the near term goal is small, cheap, and disposable for munitions.
There's much current interest in weapons which combine gun, bomb, and missile technology to boost range. Bombs with a small jet engine and wings for extra range exist. Both the US and Russia have them. Artillery rounds with a rocket upper stage are becoming available. The general idea is to have stuff you can shoot into heavily defended territory.[2]
[1] https://eri-summit.darpa.mil/docs/ERIsummit2020/posters/25_P...
[2] https://www.youtube.com/watch?v=0vIPNElDkns