'Genocide' is a powerful term — it's been called the "crime of crimes". When does large-scale violence become genocide, and why is it so difficult to prove and punish? - 'Genocide' ces yog ib lo lus muaj fwj chim heev — thiab yog lo lus siv los qhia txog ''ib co kev ua txhaum cai ntawm ntau yam kev ua txhaum cai.'' Tab sis thaum twg ib cov teeb meem kub ntxhov loj thiaj ras los ua cov xwm txheej tua ib tsav neeg (genocide), thiab vim li cas thiaj yog tej yam nyuaj heev yuav qhia tau tias yog cov xwm txheej genocide thiab muab tej neeg ua txhaum coj mus rau txim?