Goldfinger was filmed before China had nuclear weapons, yet they are a plot point. How well known the Chinese nuclear program was at the time?

In the Bond film Goldfinger, the villain's plan depends on a nuclear bomb given to him by the communist China. The film was filmed in early 1964, and released a month (September 1964) before the first Chinese nuclear test (October 1964). Was it a common knowledge at the time that China was going to have nuclear weapons soon?