What is the war goal for Imperialism? Is it full occupation?

I've so far used Imperialism three times in my Spain campaign. Of the 3 times, two of them were against small nations so fully occupying them was easy. The third against a large Tunis, I could not achieve the war goal. Is it really full occupation? If so, that's quite literally insane. You can have a country 99% occupied, no armies left. But hey, they have some random exclave location you can't see or can't get to so they still get ticking warscore as the defender. Surely this can't be intended...