“The crime of aggression is sometimes referred to as the ‘mother of all other crimes’ because it precedes all of the other crimes, war crimes, crimes against humanity, even genocide,” Iva Vukusic, an international law expert at the University of Utrecht, told The Associated Press.

Press service of the Cabinet of Ministers of Ukraine/Handout via REUTERS LVIV, Ukraine (Reuters) - Europe threw its support on Friday behind a special tribunal to prosecute President Vladimir Putin and other senior Russian officials for the crime of aggression against Ukraine,

The tribunal concerning the crime of aggression against Ukraine is an essential element of justice, and the Russian leadership must not remain unpunished. Source: Ukrainian and European diplomats at a joint press conference in Lviv,

Events to mark the holiday in the occupied territories seem to be an effort to show Russian control of land it has captured.

U.S. President Donald Trump called on Thursday for a 30-day unconditional ceasefire between Russia and Ukraine and said that both countries will be held accountable for the "sanctity of these direct negotiations.

Kyiv accused Moscow of breaching its own ceasefire on Thursday, saying Russian forces struck hundreds of times along the front lines and launched guided bombs that killed and wounded civilians in several Ukrainian cities.