The Chien Lung class of submarine, also known as the Hai Lung (Sea Dragon) class, was manufactured in the Netherlands for the Republic of China (Taiwan) and is currently in service with its navy. They are a modified version of the Dutch Navy's which itself is based on the US . A new class of submarines being built by Taiwan's Indigenous Defense Submarine program, will eventually replace them. History The Republic of China (Taiwan) ordered two submarines, each based on the Dutch Zwaardvis design, in September 1981. The keels for both submarines were laid down by dock and yard company Wilton Fijenoord b.v Schiedam in December 1982, though initial construction of the submarines was delayed due to the builder's financial instability, work resumed in 1983. Both submarines were launched in 1986, Hai Lung on October 6 and Hai Hu on December 10. Sea trials for Hai Lung began in March 1987 and Hai Hu began its sea trials in January 1988. Both ships were transported to Taiwan on board a heavy dock vessel. Hai Hu was commissioned for service on October 9, 1987 and Hai Lung followed on April 9, 1988. The deal for the submarines also included power station components and gas liquifaction plants. More boats in this class were planned, and in October 1983 the Dutch government held talks with Taiwan in which the ordering of two extra submarines was discussed. The order worth ƒ800 million was to be paid for 50% by investments of Taiwan in the Netherlands in the form of civil orders. However, the deal fell through after mainland China pressured the Dutch government. An order for four more submarines was also turned down by the Netherlands government in 1992 after China downgraded diplomatic ties with the Dutch. Design The Hai Lung-class submarines are based on an improved Zwaardvis-class design. This means that they also make use of the US Navy's teardrop hull design, which was used by the of conventional submarines. The design was modified to include the placement of noise-producing machinery on a false deck with spring suspension for silent running. As built the class featured an Elbit TIMNEX 4CH(V2) electronic support measures (ESM) system. Tasks The Hai Lung-class submarines are aimed at providing Taiwan the capability to deter Chinese naval blockades and to ensure that its sea lanes remain open, thus protecting the trade on which the island depends. In addition, both