Explainer-How could Russia's Putin be prosecuted for war crimes in Ukraine?

FILE PHOTO: Russian President Vladimir Putin delivers a speech during a concert marking the eighth anniversary of Russia's annexation of Crimea at Luzhniki Stadium in Moscow, Russia March 18, 2022. Sputnik/Sergey Guneev/Kremlin via REUTERS/File Photo

(Reuters) - U.S. President Joe Biden on Monday called for the prosecution of Russian President Vladimir Putin for war crimes over the discovery in Bucha, Ukraine, of mass graves and bodies of bound civilians shot at close range, but various challenges stand in the way.

IS TARGETING CIVILIANS A WAR CRIME?