Since Deng Xiaoping and Jimmy Carter struck a deal in 1979, American and Chinese academics have co-operated on scientific research. Like so much else about relations between the two countries, that co-operation is now under threat. As we report this week American and Chinese scientists are writing fewer papers together and the number of Chinese students and researchers entering America has fallen sharply. Now politicians are wavering about whether to renew the Deng-Carter deal, called the Science and Technology Agreement (STA). Republicans want to scrap the pact; Democrats want to renegotiate its terms. It is easy to understand America’s fears...