The author is an expert of this time because she was alive during most of the Cold War and most likely knows about weapons that were present in that time. This is why she is an specialist of this time and subject.
Suzanne Collins was inspired to write The Hunger Games Trilogy when she was watching coverage of the civil war currently happening in Iraq. She was also heavily inspired to write the books because of Greek Mythology. She also wrote it to bring to light the atrocious things