There are several criteria by which one might say that, and I'll offer one example. The evil done by Russians, Chinese, and Koreans has mostly been done to other Russians, Chinese, and Koreans. (There are exceptions, e.g. China's treatment of Vietnam, but that rather underscores the point I'm making.) USA, on the other hand, in addition to its centuries-long record of brutal colonialism and racial apartheid in North America, has a similar record of brutality throughout Latin America, Southeast Asia, the Middle East, and Africa. It would not be irrational to consider the global export of violence to be worse than its domestic use.
