In 2016, China confirmed a project to supply eight non-nuclear submarines to Pakistan. The contract, estimated to be worth around $4-5 billion, was the largest naval shipbuilding export deal signed by China till date. The contract involved construction of the first four submarines in China and the remaining units at the Karachi Shipyard & Engineering Works (KSEW), Pakistan's main military shipbuilder.
On Tuesday, a website focussed on naval developments worldwide reported there was evidence of modernisation and expansion at the KSEW facility in Karachi.
Naval News cited satellite imagery that showed the presence of a "new construction hall and dry dock at the southern end" of KSEW. Naval News noted the new construction hall could be large enough to "build two submarines in parallel".
"Work on the aligned dry dock appears to have started in 2016. It is a Norwegian designed Syncrolift ship-lift type built out over the water. Manufacture of the sections likely took place in China. The dry dock is 126m (415 ft) long and 32m (105 ft) across and has a lifting capacity of 7,881 tons. This is large enough for the new submarines, and would allow frigate sized warships and larger submarines in future," Naval News noted.
According to reports, the first of the new class of submarines, referred to as S-20, will enter service with the Pakistan Navy by 2022 and construction of all the four units in Pakistan is expected to be completed by 2028.
In 2015, when news of the possible submarine contract began emerging, then minister of defence production Rana Tanveer Hussain declared China would transfer technology for the submarine project to Pakistan.
While China has remained Pakistan's largest arms supplier, Pakistan had been using French-designed submarines for over 50 years. Its most capable class of submarines, the Agosta-90B class, featured an air-independent propulsion system that would allow the submarine to stay submerged for a considerably longer period without having to surface to recharge its batteries by using atmospheric air.
The eight submarines being supplied to Pakistan are expected to use a newer Chinese-designed air-independent propulsion system that is based on a Stirling engine that generates electricity by combustion of liquid oxygen with diesel. This is regarded as a more-efficient air-independent propulsion system than the one on the Agosta-90B submarines, which were designed in the 1990s.
The S-20 class is believed to be a derivative of the Type-039A 'Yuan' class, the newest class of non-nuclear submarines in the Chinese Navy. A report of the US Congressional Research Service on the Chinese Navy noted China has inducted 17 Yuan class submarines by 2020 and could have 25 ships of the class in service by 2025. The S-20 submarines will be armed with torpedoes and anti-ship missiles. It has been speculated Pakistan could arm its new class of submarines from China with the Babur cruise missile, giving it a nuclear strike capability.
In 2017, the then chief of the Pakistan Navy announced the eight new submarines from China would be designated the Hangor class, in honour of the first class of French submarines sold to the Pakistan Navy. The lead ship of the Hangor class, PNS Hangor, sunk the Indian Navy ship INS Khukri in the 1971 war, killing 194 Indian personnel. The INS Khukri was the first surface warship sunk by a submarine since the 2nd World War and the single worst loss of lives for the Indian Navy.