Russia is being widely accused of violating international law in its invasion of Ukraine, and now the International Criminal Court is investigating.
The US President Joe Biden has already labelled Vladimir Putin a "war criminal" - but other world leaders have not followed suit.
Jacinda Ardern is one of them - saying instead there is evidence of war crimes by Russia and its president.
Otago University associate professor of politics James Headley spoke to Susie Ferguson about the language of diplomacy.
