(
source nb - all figures rounded up or down for easy math)
Measure|Germany|USA...|Multiple USA vs. Germany
Population (MM)|80|320|4x
GDP in Trillions|4|20|5x
Emissions (x1,000 metric tons)|730|5,000|7x
Defense Spending ($B)|50|650|13x
Looking at the above, the USA has 4 times the population of Germany, 5 times the GDP, 7 times the emissions and 13 times the defense spending.
Your hypothesis (one "interesting thing") was that we might explain some of the emissions per-capita difference by our defense spending covering some of Germany's security. Germany "outsources" some of their emissions and defense spending to the USA.
The absolute difference in Defense spending is 600 Billion, while the absolute difference in GDP is 16 Trillion. Unless defense spending has a carbon impact of around 30 times that of other kinds of spending, the (relatively) small difference in economic impact wouldn't appear to be large enough in absolute terms to explain such a variance in CO2 footprint between the two countries.
So, that's a provisional "no" from me on your hypothesis / interesting thing / "not so bad" emissions difference. If my reasoning isn't clear enough, let me know and I can do some graphs, but not right now.