This was, of course, the cause of the war if the US government claimed forts on Confederate territory what was to stop it from making other claims and demands?
Yes. Imagine the US government wanting to still own forts it owned and demanding repayment of money and the return of armaments stolen by the Confederacy. The idea reminds me of my former wife who categorized everything into one of two categories. There were things that were "hers" and things that were "ours."