Little to no enemies
Lupe is drawing a contrast between what is currently happening and what the archaeologists may assume about the United States in the future.
There are no signs of war in America (just like World War 2) Why would future archaeologists assume that the USA had no enemies? Because there are no signs of war within its borders — the USA conducts all its wars and occupations overseas, far from the sight of most of its citizens!
This verse is a long metaphor for the irony within America — some are ridiculously wealthy while the government spends billions on war but there are many living below the poverty line.
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