I'm not quite sure whether the question is correctly answered here or whether it belongs to Law Stack Exchange.
Assuming I can fly into space, more precisely to the moon and back again.
What laws forbid me to collect the American flag (regardless of its condition) or any other object of a space nation and bring it back to earth?
Would that be "simple" theft?
If the country is important because of its laws, I would like to know from the perspective of the USA, China and Germany.