I don't believe our nation's flag is on the moon
Taken generally, he doesn’t believe that the moon is within the province of America simply because the US sent a man there. In other words, the moon and rest of the cosmos don’t belong to any one person or nation.
He casts this sentiment within the context of a popular conspiracy theory that the moon landing was faked in order to boost national morale during the Cold War. It is also possible that he literally believes in this theory.
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