We all know that in science-fiction movie, there is usually a colony reference.
What about in DU?
THE MAIN IDEA:
On inhabitable planets, there should be advanced and rare materials on them, encouraging to "terraform" them and allow easier resource transfers on it.
On the idea of BLOCKADES and FLEET MANAGEMENT (link coming soon),
rival factions would love to prevent transportation of live saving energy, water, food, oxygen, fuel, ect, starving the colony until it falls.
After an ample amount of terraforming, the colony should be able to survive on its own.
THE OTHER IDEAS:
Enemies could be able to impersonate the alliances, getting free resources while the friendly alliance will wonder what their stuff has gone.