Visiting US President Barack Obama, addressing Israel students in Jerusalem Thursday, said politicians don’t take risks unless urged by their people. His audience rose and cheered him when he said Israel has the right to exist and is not going anywhere. You are not alone, he said in Hebrew; America is Israel’s greatest friend. America will do what it must to prevent a nuclear Iran, he said. But shouts of protest were also heard amid the applause when he called for peace and justice for the Palestinians.