For GPS tech there are several so far hypothetical weaknesses, including degraded signals from atmospheric effects and signal blocking buildings, this might explain some of the misses if not malfunctions. If someone is crazy enough to use nuclear weapons a series of very high altitude bursts would be enough to knock out all of the relevant US GPS satellites in a region (potentially every satellite in orbit), rendering the accuracy back to dumb bomb status. Then there's direct attack against the satellites and jammers but no one's got the tech to do the former and the latter's efficacy is unknown and prolly "countermeasured" against already.
As a former field marine, I'm not for sure on this, but wouldn't you think that the GPS satellites, being a product of the Cold War, would be hardened against EMP (Electromagnetic Pulse, which can fry unprotected circuitry like bacon on a grill)? I'm not for sure on this, but I think you're right as far as why the GPS-guided JDAMs are never perfect. Buildings and topography could get in the way, but would that matter on the terminal phase of the bomb?
States and schools can't pay their bills, but we have hundreds of billions to throw at an unnecessary and ridiculously inaccurate space weapons program that would prevent absolutely nothing.
We currently spend quite a lot on forward deployed forces. No idea how the two compare cost-wise, but it does sound like this is intended to replace those expeditures. And one should never underestimate the civilian spin-off gains to our economy that come out of DARPA projects. Like......uh.....the internet?
Rewarding states for their out-of-control spending by bailing them out at the Federal level is tantamount to rewarding an alcoholic by giving him a beer tap in his living room. We spend more money on schools (adjusted for inflation) then at any time in our history, yet most students can't even name 25 of the 50 states, balance their checkbooks, or even name our first president. Wow, that's money well spent! On this so-called "unnecessary" program, the whole point of such a great undertaking is deterrence! Most nations would think twice about attacking our interests if silver bullets rained hell on them from above without any hope of them defending themselves against these wonder weapons. Anything that saves the lifes of Marines (Semper Fi!), sailors, soldiers, airmen and coasties is worth any amount of money in my book. Besides, the spinoffs in civilian technology may yield a cheaper way for us to get satellites in orbit and replace those flying artifact space shuttles.
The more we spend on any space based technology, the closer we are to colonizing other planets/moons. The amount of natural resources we can get from the rest of the galaxy dwarfs anything we spend to get there.
You are right. They couldn't absorb a far miss though and one would only need to knock out about four to eliminate US GPS tech from your launch site. The question is, would the US consider this a first strike. There are some papers on the high altitude nuke tests in the 70's having an extremely effective kill rate on satellites due to Van Allen belt disturbances.
