Tiaral

Here's the thing.
In offensive missions, you can theoretically play defensively. To do this, you need to occupy a convenient position, engage in some minor looting in the surrounding area, and wait for them to try to dislodge you. But technically, it's unlikely to be that simple.
In defensive operations, you can attack. Technically, this seems easier; you just need to move more actively than the enemy and take the initiative, without worrying that the territory is friendly and you can "hunker down." The risk is that in some situations, it might actually be much easier to "hunker down," or rather, in a fortress.
Of course, this is assuming that Reven hasn't created a system that prevents this, because I don't know.