You will have to file as a resident of Indiana even though you are living overseas.
If you are a U. S. citizen working for the US Government, including the Foreign Service, and you are stationed abroad, your income tax filing requirements are generally the same as those for citizens and residents living in the United States. You are taxed on your worldwide income, even though you live and work abroad. However, you may receive certain allowances and have certain expenses that you generally do not have while living in the United States.
Reference: https://www.irs.gov/individuals/international-taxpayers/us-government-civilian-employees-stationed-a...
