	When Tsien had returned from China with his new bride in 1947, he had answered "no" on an immigration questionnaire that asked if he ever had been a member of an organization advocating overthrow of the U.S. Government by force. This, together with an American Communist Party document from 1938 with Tsien's name on it, was used to argue that Tsien was a national security threat. Prosecutors also cited a cross-examination session where Tsien said, "I owe allegiance to the people of China" and would "certainly not" let the United States government make his decision for him as to whom he would owe allegiance to in the event of a conflict between the U.S. and communist China.