Nukes Have Worked Since 1945 - Why Keep Affirming That - Nuclear Tests Thru 1989?

unless the goal is to a) destabilise the west coast of USA (which has happened) or the Russian continent or the mid-Pacific or b) destabilise the health of humans around the world, why all these nuclear detonations thru 1989?
We know nukes have worked since Oppenheimer's Trinity i.e. July 16th 1945, what's the point of RE-TESTING NUKES on this global scale?