April 23 (UPI) -- Late last year, Paraguay expelled a Chinese diplomat after he appeared uninvited before Congress and told lawmakers they had to choose between Taiwan and China. The episode was striking: a small, landlocked country of seven million sending away an envoy from the world's second-largest economy. But it revealed something larger than a breach of diplomatic protocol. It showed how trade and investment can become tools of pressure, not just pathways to prosperity. That pressure is