Twitter was scrabbling to defend the appointment of a Chinese head with government ties, yet US tech has a busy revolving door with its own government What’s worse for a Silicon Valley executive: ties to the Chinese military or friends in the US Defense Department? Twitter found itself confronting that question this week after it hired Kathy Chen, a former engineer for the People’s Liberation Army (PLA), to head up ad sales and business development in China, Hong Kong and Taiwan. Internet freedom activists and Chinese dissidents, who have to skirt Beijing’s digital censors to use Twitter, said it was a betrayal. The spat illustrates the delicate balancing act technology companies face as they are forced to expand overseas to grow. In the US, Silicon Valley, like any industry, has embraced and relied on close relationships with former government officials both for technical talent and to help grease the wheels as they confront regulatory issues. Alphabet’s executive chairman, ...