ATHENS, GREECE - JULY 1: In this handout photo provided by the Greek Prime Minister's Office, Greek Prime Minister Alexis Tsirpas delivers a televised address to the nation from his office at Maximos Mansion on July 1, 2015 in Athens, Greece. Mr Tsipras has vowed to push on with his plan for a referendum this Sunday on the recent proposals from the country's creditors. (Photo by Greek Prime Minister's Office via Getty Images)