you pay tax on that $100k in the year that you made the money, where the money is sitting is irrelevant
if you made the money in the U.S. then the IRS requires tax returns to be filed as well, but there is a tax treaty where you are not taxed twice on the same income, but you must file in both countries
this is my understanding and how I have done it, but I am not a tax expert so my disclaimer is that the above is only my opinion and should not be taken as legal or taxation advice