Question: At the very beginning, it says that a family got stranded in a desert. Is it referring to the Carter family from the first film?
Question: Isn't the National Guard supposed to be in the US only? Then why did the sergeant talk about them being in Kandahar?
Answer: The President of the United States could have sent them there. Remember G.W. Bush sent some National Guard troops to Iraq and Afghanistan during the wars.
Answer: Yes it is.