China's submarine program is moving along, but not steadily. The type-092 Xia-class nuclear-powered ballistic missile submarine has just undergone a five-year refit (which was supposed to be a three-year refit), but will not go to sea anytime soon as it is simply too unreliable. The new type-093 nuclear-powered attack submarine program is behind schedule and the first boat is not expected to enter service any sooner than 2006. The type-094 nuclear-powered ballistic missile submarine will use the same basic hull and propulsion plant as the Type-093. The JL-2 ballistic missile has not been test fired. There are disputed reports as to the status of this sub, with some sources saying one has been launched while others insist it is still on the drawing boards and that no work will be done on this until the sea trials of the first type-093 are completed. By all accounts, the two designs are very similar and one could easily have been reported as the other. The 20th Ming-class diesel-electric submarine has been completed. It is two meters longer than the 76-meter length of the first 19 boats of this class. As the additional space is in the engine room, it is assumed that this boat has a larger engine, or may include an advanced air-independent propulsion plant. The first of the Type-039 Song-class diesel-electric submarines was completed in 1995 but only proved that the design needed a major re-think. The second Song-class boat has conducted a year of sea trials but seems no closer to deployment or series production.--Stephen V Cole