I have not yet read convincing (for me) arguments for those installations for I share McGrath's implicit (and explicit) fears that such installations though they might be useful in case of an attack may make such an attack more likely (or more severe) in the first place.
But there's one thing that makes me thinking twice: Vaclav Havel, former president of Czechoslovakia supports the installations for the Czech Republic. And Havel is a first class "peacenik". What brings such a man to this opinion? I have read that he supports the installations but have not read yet about his reasoning.