If you mean "back into the US," then indeed there is the potential to continue sitting on that money and maybe it won't enter the US economy.
If, however, you do mean to ask "...back into the US economy," then ... jobs. How they choose to place the money into the economy is definitely a question, but ultimately any use should indeed support employment of the labor force. Loan the money out? The borrower puts someone to work. Use it for R&D? Hire humans to perform the research.
If, however, you do mean to ask "...back into the US economy," then ... jobs. How they choose to place the money into the economy is definitely a question, but ultimately any use should indeed support employment of the labor force. Loan the money out? The borrower puts someone to work. Use it for R&D? Hire humans to perform the research.