[Q]

Originally posted by MegaTrain:
That's the problem. I don't want to destoy all population and facilities on the planet, because I'm using this to force surrender.

But then why do you want to destroy the weapon platforms at all?
In this situation I use the "don't get hurt" strategy and blockade the planet. The ships will still defend themselves if attacked by ships/fighters/drones but will not at all attack the planet and stay out of range of its weapon platforms.