Economic Data Tidbit -- Defense Spending

From the Economist Pocket World in Figures:

Defense Spending (in Billions $)

1. United States 495.3
2. China 104.0
3. France 53.1
4. United Kingdom 51.7
5. Japan 43.9
6. Germany 38.0
7. Italy 31.4
8. Saudi Arabia 25.4
9. India 21.7
10. South Korea 20.3
11. Australia 15.6
12. Brazil 13.3
13. Spain 13.2
14. Canada 12.8
15. Turkey 11.7
16. Netherlands 9.9
17. Israel 9.8
18. Indonesia 8.4
19. Taiwan 8.0

So, the good old US of A lays out nearly half a trillion in defense spending and the next 18 nations in total drop ALMOST as much. I understand the "cutting edge" argument that holds that to stay preeminent a significant additional investment is needed. I also understand that as a percentage of GDP, the USA is only at 4.0% (20th in the world), which is significantly below the over militarized Middle East norm of 6-8%. These arguments or defenses (no pun intended) for military spending do have merit, but at the end of the day --- the US still spends nearly 5 times what China spends... Somehow I doubt the marginal benefit of the last $100 billion is all that high.... But I could be wrong, and if lowered these expenditures and something happened then it would be my fault...