An American family on active military duty, living on an American military base in Europe adopts a child, is this child a US citizen?

An American family on active military duty, living on an American military base in Europe adopts a child, is this child a US citizen?

Answer

This child will not become a US citizen until the family returns to the USA with the child as an immigrant. In this case the child becomes a US citizen upon arrival in the USA. Or the child can be naturalized at a designated base in Germany or Italy after the parents apply for naturalization by filing form N-600K.