The general consensus by scientists for decades has been that a Star Wars program is ineffective and costly. There was a long piece in Scientific American (back when it was still a respectable scientific journal) around 1985 that lambasted the whole Star Wars scheme. There were plenty of reasons, but it essentially distilled to this: it's hard to make a shield, and easy to make countermeasures.

Lasers? Use reflective film or a shell that can burn off. Radar? Use decoys. Lots of them. Shrapnel? Throw more nukes their way. Fancy computer tracking? Also more nukes. These are all cheap countermeasures.

The shield has to be perfect, while just one nuke has to make it through. And that ignores shipping the nukes in. Sir, you've received a FedEx, express from the Kremlin.