From what I remember the last time a space-based weapon was attempted in any known way, launched was the Russian Polyus. Not an orbital bombardment platform, but it made as a countermeasure to SDI.
But that doesn't matter much, because its guidance failed and instead of boosting itself into a circular orbit, it kicked itself in reverse and burned up on reentry.
Also, minor extra: Any kind of orbital weapons platform would need to be lifted into space for obscene amounts of money, will have a perfectly predictable path, so would be under pretty much constant observation, its payload would have severe issues being controlled and/or retargeted, and if you want kinetic weaponry, you'll need heavy, heavy tungsten rods, which hit about as hard as a cruise missile without any of the perks of being maneuverable and easily controllable.
In any case, if it's nukes, you can't have them unless you hide them really well, and if it's conventional, you're **** out of luck until you can build the entire thing in orbit.