BEIJING (Reuters) -China's defence minister on Thursday urged greater efforts for global unity, warning against an increasingly divided world "defined by the rule of the jungle". Speaking to formally open the Beijing Xiangshan Forum on security, Dong Jun said the world was overshadowed by Cold War thinking, hegemony and protectionism - a veiled swipe at the United States. "An obsession with absolute superiority in military strength and a 'might is right' approach will lead to a divided world defined by the rule of the jungle and disorder."