Just using the CIA Factbook to put the military angle in perspective..
USA
Total: 9,631,418 sq km
Population: 295,734,134
GDP Total: $11,750 Billion
GDP per capita: $40,100
Military Expenditure: $370.7 Billion
China
Total: 9,596,960 sq km
Population: 1,306,313,812
GDP Total...