Not really as to do what was being pitched (protect the US population from nuclear attack) you have to have an over 99% intercept rate which wasn't going to happen in any likely war scenario. Most of the more effective programs were also the most expensive and the lower cost (for a given value of 'lower' of course
) were not as effective so would require many more systems to reach an acceptable level. It would have been horribly expensive either way.
And the 'counters' to the system were 'easy' and 'cheap' enough to drop your intercept percentage into the low 70% which then requires a more extensive system and the cost soon becomes prohibitive even for the US.
Now something to keep in mind is the military had a different plan for SDI which didn't require such a high "general" intercept rate and that was to use SDI to protect the missile fields, bomber and sub bases and let the rest of the warheads through. You might guess that this would not have set well with the public or the politicians and you'd be very correct. But it was a vastly more 'doable' way to go about it since it would ensure that no "first strike" took out our ability to retaliate.
Of course the MAIN issue was that the most 'effective' (and obvious
) counter is to launch before the system is in place while your weapons are still effective and before you rack up too much costs in countering the system and that's why a lot of the experts called SDI "destabilizing" because it was. Deployment of anything over the allowed "limited" systems means that the opposition (the Soviets in this case) HAVE to counter and given they were already in economic trouble doing so would be a no-win scenario which very clearly puts all the other "no-win, but maybe survive" scenarios on the table.
Considering it was a replacement for using IRBM launched nuclear anti-satellite weapons we'd had standing by since the late 50s it was generally a success but not really seen as something that would be viable during an actual war where we'd fall back on "nuking" everyone's (including our) orbital assets anyway. Really the parallel Navy program to upgrade the Standard was a more viable means of deployment.
Randy