Pakistan began the construction of its Hangor-class guided-missile attack submarine at Karachi Shipyard on Thursday.

The steel cutting ceremony of the submarine coincided with the 50th anniversary of the sinking of Indian Navy warship INS Khukri by a French origin Hangor class submarine in the 1971 war.

On steel cutting ceremony of 5th HANGOR Class Submarine, the first to be built indigenously in Pakistan. #CNS expressed gratitude & acknowledged deepening ties of Pak & #China. #50thHANGORDay — DGPR (Navy) (@dgprPaknavy) December 9, 2021

The construction of the Yuan-class submarine is part of a $3 billion deal under which eight diesel-electric attack boats will be delivered to the Pakistan Navy by 2028.

Karachi Shipyard and Wuchang Shipbuilding, a Wuhan-based subsidiary of the state-owned China Shipbuilding Industry Company (CSIC), are responsible for delivering eight air-independent propulsion (AIP) powered submarines to the Pakistan Navy, with the first four already under construction in Wuhan.

Three more submarines will be constructed in Karachi.

The 77.6-metre long submarine has a submerged displacement of 3,600 tonnes, higher than the Type 39G Song class and Project 636-kilo class.

The Pakistani Hangor-Class subs will also be armed with six torpedoes and nuclear Babur-III cruise missiles.

Pakistan has also signed a deal with Turkey to modernise its four submarines while its shipyard is indigenously developing midget submarines for overt and covert operations.

With rising susceptibility to subsurface attacks from Pakistani waters, the Indian Navy also plans to induct diesel-electric mini-submarines with a displacement capacity of less than 490 tonnes.

The 44 metre-long midget submarine will be fitted with conformal-array sonar and radio frequency sensors for detection, surveillance, planting limpet mines, communication, and interception.

Last month, Indian Navy chief Admiral Karambir Singh also admitted that the force closely monitors the ongoing cooperation between China and Pakistan.

"A lot of hardware is being exported to Pakistan from China, like ships and submarines. This will affect a lot the security dynamics here. We have to be prepared for this," Singh said on 25 November in Mumbai after commissioning a French Scorpene-class submarine into the Navy.

Singh responded to a question on China delivering Pakistan its largest and most advanced warship PNS TUGHRIL on 9 November.

TUGHRIL is the first of four Type 054 Frigates constructed for the Pakistan Navy at Hudong Zhonghua (HZ) Shipyard, China.

Pakistan ambassador to China Moin ul Haque said that the frigates will strengthen Pakistan Navy's capabilities to respond to maritime challenges to ensure seaward defence, maintain peace, stability, and balance of power in the Indian Ocean Region (IOR).

Presently, the Indian Navy dominates the IOR. Still, it has been facing competition from China's People Liberation Army-Navy as India claims that 7-8 Chinese warships are present in the IOR at any given time.

The PLA Navy also deploys submarines occasionally in the IOR to patrol China's energy shipping vessels.