For USA, I think it's just hard not to take some interest in it if you like politics. Given how they affect the global outcome. As for Japan, I love all things Japanese so their history, culture, sports, news, politics is all interesting to me.
You're lucky to have done history at AS, I couldn't choose history due to how they placed the timetables together
And my favourite historical book would be
The Rising Sun - The Decline and Fall of the Japanese Empire 1936-1945 by John Toland. And yes, past military conflicts interest me.
As for the riots I mentioned..well it was due to a chain reaction of events. A well known Sikh activist called
Jarnail Singh Bhindranwale was opposed to much of what the government did at the time. He was in favour of much of what was proposed by the
Anandpur Resolution. He then set up base in the Golden Temple.
Indira Gandhi, prime minister of India at the time, and a lot of other politicians viewed this group led by Bhindranwale as extremists, since weapons were being amassed in the Golden Temple. She ordered Operation Bluestar to remove them. And that led to tanks, and other military action being used on the most holy area in the Sikh religion. Bhindranwale was killed amongst others.
In response, two of Gandhi's bodyguards who happened to be Sikhs assassinated her by shooting. This led to the
1984 Anti Sikh Riots, a massacre of the Sikh community in India. About 8000 were killed.