May 10 (UPI) -- European leaders from Britain, France, Germany and Poland joined Ukrainian President Volodymyr Zelensky in Kyiv on Saturday in urging Russian President Vladimir Putin to accept a 30-day unconditional ceasefire or face more sanctions. British Prime Minister Keir Starmer, French President Emmanuel Macron and Germany's Chancellor Friedrich Merez traveled in a train together to Kiev, and Poland's Prime Minister Donald Tusk was aboard another train, the Guardian reported . Zelensky