1. The Song-class submarines are diesel powered, and are probably 5-generations behind. This type of sub can be detected easily with conventional approaches as well as by satellites. 2. In open sea, an aircraft carrier can easily outrun the slow sub, making it very difficult for it to stalk. 3. The commander of the 7th fleet does not believe that the Chinese subs are capable to be a threat. 4. This kind of news have been released often recently.