I have enjoyed watching you outline 15 years of SDI in three paragraphs.

My father was tracking satellites during Starfish Prime. Three of the four satellites he was tracking were taken out by radiation belts. The problem with nuclear explosions is they send energy, radiation and particles in Newtonian directions from the point of origin, which then orbit the planet in a Newtonian fashion. Starfish Prime was 1.4MT at 400km and it lit up the Van Allen belts and made some nasty artificial radiation belts of its own. I think it's safe to say that wherever the Russians lit off their theoretical candle, it'd pollute a big chunk of the airspace there for a while.

Most people who looked at Project Excalibur at the time doubted whether LLNL were capable of developing it properly, and they had a blank check. It's a dumb fucking idea. The bugabear of SDI was "how 'bout we just quadruple our decoys" because if the Russians sent up twice as many lumps of shit as they sent up warheads, they double their effectiveness against countermeasures without appreciably increasing their expense or sophistication. The bugabear of the '80s, the R-39 (or "SS-N-20 Sturgeon" as reported in Soviet Military Power), famously carried up to ten warheads. Realistic load-out was two or three with seven or eight decoys.

Meanwhile, there are rumors that the MIRVs in the Topol M are capable of evasive maneuvers but it appears your choices are 3-4 ballistic MIRVs or 1 that can wiggle.