US President Joe Biden on Wednesday flatly called Russia’s Vladimir Putin a “war criminal” for the unfolding onslaught in Ukraine, where hospitals and maternity wards have been bombed. But declaring someone a war criminal is not as simple as just saying the words. There are set definitions and processes for determining who’s a war criminal and how they should be punished.The White House had been avoiding applying the designation to Putin, saying it requires investigation and an international…