Turkey could be deemed responsible for summary executions by an affiliated armed group of captured Kurdish fighters and a politician, acts that may amount to war crimes, the United Nations said on Tuesday. The U.N. human rights office also said it had documented civilian casualties caused by air strikes, ground-based strikes and sniper fire each day since the Turkish offensive began in northeastern Syria nearly a week ago. Turkey and its Syrian rebel allies launched a military offensive into Kurdish-held parts of the northeast saying it aims to defeat the Kurdish YPG militia which it sees as terrorists for its links to separatists in Turkey.