Satellite mounted weapons systems that can block ballistic missiles, i.e. reach at least into the upper atmosphere, but can't ever be used offensively? That see

Satellite mounted weapons systems that can block ballistic missiles, i.e. reach at least into the upper atmosphere, but can't ever be used offensively? That seems like a tall order. In addition, anything making MAD impossible will have very, very far reaching consequences for world politics, many of which are offensive. Any state that can unilaterally deploy nukes without fear of reprisal is on it's way to the total global tyranny you mention.