At this point you can pool any or all of your stockpiled RUs to a world that you own.  This is a convenient way to gather all of your RUs in one place and then disburse them as you see fit.  RUs at blockaded worlds cannot be shipped off-world for pooling purposes, but RUs can be pooled to a blockaded world.
 
 
Allies: Allied empires can pool RUs to either other's worlds.   If you pool your RUs to an ally's world, your RUs will be maintained as a separate stockpile at that world for as long as the alliance lasts.  If the alliance is later broken, the world's owner immediately takes possession of any non-allied RUs stockpiled there.  Similarly, if the owning empire loses control of that world, the new owner will take control of all separate stockpiles, unless the new owner is also an ally of the stockpile's owner
 
 
Abandoned Empires: Abandoned empires pool RUs at the owned world with the highest friendly-DP-to-foreign-gun ratio.