Displaying improved relations between China and Taiwan, the two sides exchanged prisoners.
The announcement of the exchange of prisoners has been made public now, but the event actually took place in mid-October.
According to the New York Times, China had released two officers, Chu Kung-hsun and Hsu Chang-kuo, from Taiwan's Bureau of Military Intelligence, and they were returned to Taiwan.
The two had been arrested in Vietnam near the border with China in 2006 and given life sentences, which were later reduced to 20 years.
A Chinese spy imprisoned in Taiwan, Li Zhihao, who was jailed 16 years ago, was given early parole as part of the exchange.
Taiwan President Ma has been broadly friendly towards China during his time in office, boosting tourism and trade ties.
Earlier this month, President Ma met Chinese President Xi Jinping in Singapore. It was the first time the leaders of China and Taiwan had held talks in more than 60 years.
