I am not a military officer, so I can offer you the knowledge only to the best of my ability. We are developing our own submarine forces. As was reported, the first one will be completed next year. For the first batch of submarines, we have a contract for eight. That's going to be a very important part of our self-defence.
For now we are working with our allies—the U.S. and Japan more than anyone else—on surveillance of undersea activities. We know that the Taiwan Strait, the East China Sea and the Yellow Sea are not deep enough for submarine activities. This is why China will not cave in on its activities in the South China Sea: The South China Sea is deep enough to hide the submarines it built in Hainan province.
If they have only one submarine base, it's easy to monitor. You know how to do it. They need another alternative. They think the eastern side of Taiwan is most ideal. The eastern coast of Taiwan is very close to a very deep seabed in the Pacific, so we don't take it lightly when they say that they have ambitions for Taiwan.