Israel has a "right of return" for any jew. If you're Jewish, you can go there and join the IDF. I don't know why you would want to, but the option is there.
The South Koreans make you relinquish your citizenship when you become an adult if you're an also an American citizen; otherwise they will scoop you up for mandatory military service.
For reference, many US citizens also served in the British or Canadian militaries in WWI and WWII prior to our entry into those wars.
Israel has a "right of return" for any jew. If you're Jewish, you can go there and join the IDF. I don't know why you would want to, but the option is there.
The South Koreans make you relinquish your citizenship when you become an adult if you're an also an American citizen; otherwise they will scoop you up for mandatory military service.
For reference, many US citizens also served in the British or Canadian militaries in WWI and WWII prior to our entry into those wars.