BEIJING/OTTAWA (Reuters) -Diplomatic tensions between China and Canada are rising again, with each country accusing the other of using their military aircraft flying near North Korea of provocation and harassment. Earlier on Monday, China’s foreign ministry warned Canada of potential “severe consequences” of any “risky provocation,” after Canada’s military last week accused Chinese warplanes of harassing its patrol aircraft monitoring North Korea’s compliance with sanctions. “The U.N. Security Council has never authorized any country to carry out military surveillance in the seas and airspace …