A United Nations court sentenced former Bosnian Serb leader Radovan Karadzic to 40 years in prison for genocide, crimes against humanity and war crimes during the Bosnian war in the 1990s. He will appeal the ruling.

The International Criminal Tribunal for the former Yugoslavia on Thursday found Mr. Karadzic guilty on 10 of the 11 counts, including genocide for the Srebrenica massacre and criminal responsibility for the shelling of Sarajevo, during a nearly four-year siege on the city. He is the highest-ranking official the...