Yes... this is a common misunderstanding.
Protection is entirely centred around space defences... not sure if STO weapons will count though, perhaps they should.
But what does count is stations in orbit or ships with some kind of weapon system on them.
Ground troops role is to police and repel invasions. So if you have unrest on the planet then you will need ground troops to suppress that unrest. So you can use troops to suppress the unrest you get from not having the space protection necessary, so in some way you can use troops as one form of "protection".
