Despite howls in some circles (right up to the four star level), the "threat" from China's 60 or so submarines seems very limited. Rarely are there more than 4-6 boats at sea at any time, often there are none at all, and a number of units (the Han nuke boats, for example), seem never to go to sea at all. China's Type 092 SSBN Changzheng, laid down in 1978 and commissioned in 1987 (NATO designation: Xia class) seems to be a maritime basket case. Reportedly it has never operated outside of Chinese territorial waters, and has never made an operational cruise. In addition, by some accounts it has been in "overhaul" since 1995. Apparently, when Chinese subs do go to sea, the usually do so accompanied by one or more surface units. This suggests a certain lack of confidence in the effectiveness of Chinese boats. China is trying to improve this situation, and has been particularly vigorous over the last few years. But so far, results are meager.