https://www.reuters.com/article/us-facebook-zuckerberg/zuckerberg-defends-facebooks-approach-to-free-speech-draws-line-on-china-idUSKBN1WW2LJ >Facebook Inc Chief Executive Mark Zuckerberg on Thursday defended the social media company's light regulation of speech and lack of fact checking on political advertising, while citing China's censorship as a roadblock to operating in the country.