How much did Japan and other smaller nations like Hungry contribute to the Axis Powers strength in WWII? What made Japan such a threat to other nations like the USA and the Soviet Union?
Kennedy details warmaking potential in his Rise and Fall of the Great Powers as follows:
| Country | % of Total Warmaking Potential |
|---|---|
| United States | 41.7% |
| Germany | 14.4% |
| USSR | 14.0% |
| UK | 10.2% |
| France | 4.2% |
| Japan | 3.5% |
| Italy | 2.5% |
| Seven Powers (total) | (90.5%) |
So Japan contributed roughly 17% of the three tripartiate members of the Axis's war potential. This was a pittance, especially compared to the United States, but there were several advantages to Germany. One, Japan had an antagonistic position with both the Soviet Union and Britain/France. The Germans in the aftermath of WWI cultivated as many alliances as they could with countries that were antagonistic towards the former Entente, which ranged from China (who were angered by European concessions) to Japan (which had a period of anti-American and anti-British sentiment through the 1920s and 1930s) and even the Soviet Union itself. Japan just happened to have enough military strength to be a potential military threat in the timeframe of Germany's choosing.
Japan ultimately was a relatively small threat compared to Germany, especially when compared to the US. However, it had a large navy (which Germany did not) and was able to threaten British and Dutch possessions in Asia (including India and Malaya) which Germany thought would be necessary to tie down British forces. German intelligence supplied information to the Japanese on the weakness of British defenses in Singapore and Malaysia for this purpose.