The left Bank

How many historical examples can you find of countries refusing to take back territory that was once, in some form or another, theirs?

That's Tyler Cowen writing about Jordan's lack of interest in taking back the West Bank. His example?

Could Puerto Rico be an example? Maybe the U.S. would gladly "give it back" (that is debatable, however) but it seems that Puerto Rican voters don't want full, unencumbered title.