How to analyse the effects of fiscal deficits? The current example of the United States

When a country runs a very large fiscal deficit (which is the case currently in the United States), what are the logical steps to analysing the effects of this deficit? What is the situation regarding private savings? If private savings do not increase, there will be savings shortfall ( ex ante ). Is the supply of imports flexible? If the answer is yes, the savings shortfall will lead to a larger external deficit - not to inflation - and to a rapid accumulation of external debt. How are the capital flows needed to finance the external borrowing attracted? Interest rates may rise significantly relative to the rest of the world. If this is not the case, the exchange rate must depreciate.