Due to his adherence to an approach to politics called Realpolitik, which prioritizes pragmatic geopolitical considerations over moral or ideological values, Kissinger has been criticized for turning a blind eye to war crimes committed by American allies during his tenure.[6]
A number of activists and human rights lawyers have sought to prosecute him for war crimes committed by American allies during his tenure.[8][150] Kissinger has been associated with such controversial policies as the U.S. bombing of Cambodia during the Vietnam War, U.S. involvement in the 1973 Chilean military coup, a “green light” to Argentina’s military junta for their Dirty War, and U.S. support for Pakistan during the Bangladesh Liberation War despite a genocide being perpetrated.[255]
Why does everyone hate him? What did he do?
From Wikipedia:
https://en.m.wikipedia.org/wiki/Henry_Kissinger
So the average secretary of state in the 20th century