China and the United States (US) crossed swords Saturday ahead of an Asia-Pacific Economic Cooperation (APEC) summit, duelling over protectionism, trade tariffs and "chequebook diplomacy" as they laid out sharply contrasting visions for the Pacific Rim region.In combative back-to-back speeches at a business forum held on a hulking cruise ship moored in Port Moresby, Xi Jinping and US Vice President Mike Pence pulled few punches.The feisty exchanges laid the ground for what could be