It's not about Nation, It's all about national interests.
Few people call Russia bad, Few US, Few China. Few used to say about UK, Spain, Germany, Japan till WW2.
Japanese invasion in china was one of the biggest genocide in last century, I suppose. - Are Japanese Bad ? NO.
German invasion in most of the neighbour countries including holocaust of Jews were biggest genocide - Are German Bad ? No, Apparently I like Germans. It happened because of Hitler, Even I don't hate Hitler, I like him except (Jews holocaust)
After Russia captured Berlin, Do you know what happened ? Another genocide. Are Russians are bad ? NO.
US Invasion of Vietnam, African country, Supporting Pakistan was big genocide. Are they doing same in Afghanistan ? NO, I suppose they are doing good job in killing those Talibanis.
It's all about perception from different POV. Every year, Japanese celebrate Invasion of China on other side, Chinese hate Japanese more than anyone else. Few mistakes do happen and sometime it becomes genocide. Government do know most of the things, They might not support such things, But they can't stop misery of other people, because their country interest is more important.