The meeting started with a handshake, but the mood was tense and there were few smiles as Chinese President Xi Jinping and U.S. Secretary of State Antony Blinken met in Beijing's Great Hall of the People on Monday. Still, just this — the fact that Washington's top diplomat and China's top leaders could meet and spend hours in "candid, substantive, and constructive discussions," according to Blinken — was seen as an accomplishment. Such is the chill in relations between the two world powers, who have accused each other of spying from balloons over each other's territories, and instigating dangerously close…