system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are there US military bases in different countries like Japan. Is there Japanese military bases in the US?

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gpt
The US does not allow it. In instances like Japan and Germany part of the agreement at the end of ww2 was that we would maintain a military presence there to assist in their national defense. Much is the same with South Korea and various other countries, to assist in our allies defense. We (the US) on the other hand feel there is not enough for us to gain, to much risk versus reward, from a country by letting them have a base on our soil.