The ship started firing its shells on Dwarka city, and the shelling continued for more than 20 minutes. A fleet of seven Pakistani ships – PNS Babur, Khaibar, Badr, Jahangir, Alamgir, Shah Jahan and Tipu Sultan – had chosen Dwarka for attack, to destroy the radar station. Fortunately, most of the shells failed to explode, and there were no human casualties. During this mayhem, INS Talwar was in Okha (a few miles north of Dwarka) for repairs, aware of the explosions and transmissions from Pakistani warships – but could do nothing in response. Other Indian warships were ordered not to get involved. The Pakistani fleet soon headed back to Karachi, with no casualties.

In 1970, Admiral Sardarilal Mathuradas Nanda had taken charge as the eighth chief of the naval staff of the Indian Navy. By mid-1971, it was evident that another India-Pakistan war was approaching, with the East Pakistan/Bangladesh issue as the trigger.

The admiral, along with chief of army staff General Sam Manekshaw, aimed to also attack rather than merely defend. The plan chalked out for the Navy was:

1. Surround the East Pakistan coast and block all ports for enemy activity, which meant denying trapped Pakistani soldiers opportunities to flee.

2. Attack Karachi. All the external trade and transfer, including that of arms and ammunition, took place at Karachi port. It was also the headquarters of the Pakistani Navy as well as its principal oil storage facility.

Admiral Nanda organised the Navy into two independent fleets – Eastern and Western – on 16 October 1971. Considering the importance of manning the sea border of East Pakistan, the aircraft carrier Vikrant was transferred to the Eastern fleet.

As far as Karachi was concerned, the plan was to attack Karachi with missile boats. This was Operation Trident. (Note: Users unaware of warship types can check here for reference).

India had acquired 8 Osa-I class missile boats from the Soviet Union in 1969. They were inducted into the Navy and categorised as Vidyut class missile boats. The boats were tested near an unknown island off the coast of Bombay – monitored by Ilyushin Il-14 and Alize aircraft (to prevent any sightings by other aircraft). After Pakistan declared a national emergency on 23 November 1971, three of the missile boats were deployed at Okha to carry out patrols and gain experience. The entire missile boat fleet was labelled as Killer Squadron 25 (K-25) and was placed under Commander Babru Bhan Yadav.

Due to their obvious weaknesses, such as shorter radar range and a less-than-sufficient anti-aircraft system, a squadron made exclusively of missile boats was not enough to attack Karachi. Two anti-submarine Arnala class (originally Soviet Petya class) Corvettes (smaller-size frigates) – INS Kadmat and INS Katchal – were added to the squadron; as the Corvettes had better radar, anti-aircraft and anti-submarine defence systems, they were to provide cover to the missile boats from air or submarine attacks. The Corvettes were also intended to provide communication, control and identification of enemy targets (due to better radar systems). Due to unexplained reasons, INS Kadmat was replaced by INS Kiltan at the last minute.

Now that the squadron was formed, another worry was the low range of missile boats due to small fuel tanks (as well as a different fuel type from that of the Corvettes). This was solved by establishing special fuel depots at Okha and Diu (on Gujarat coast). Also, a fleet tanker ship, INS Poshak, was added to the squadron to be positioned halfway from Karachi, to refuel the missile boats both before and after the final lap of the attack.

Air Attack on Karachi and Badin

Any successful military attack on enemy soil has to involve neutralising its air-attack capability. In this case, it was even more important, as missile boats do not have adequate air defence systems. There were two air bases which would have served as springboards for Pakistani air attack – Masroor (Karachi) and Badin. The request to bombard these two was promptly raised by admiral Nanda. The proposal was executed swiftly.

The day, 4 December, saw day-long air strikes on Masroor and Badin. The strikes destroyed the Badin radar station and warehouse. Pakistani Navy thought these were part of routine firing.

Operation Trident Begins

4 December 1971. The squadron started its 500km-long journey to Karachi from Okha. Due to shorter travel ranges, missile boats were being towed till a certain distance to Karachi harbour. Complete radio silence was to be kept till the squadron reached closer to the Karachi naval base. The squadron formed an arrow-head formation, with INS Nipat leading the way, INS Nirghat five miles to its port (left) and INS Veer on starboard (right). Another advantage for the Indian squadron was the fluency of its crew in Russian. This would prove to be very useful while communicating.

2000 hrs: The squadron inched up to Karachi at a speed of 24 knots (approximately 44.5kph). Dusk had fallen. The squadron had a stroke of misfortune as well as good luck. The misfortune had to do with the fact that it was a full moon night, making it frighteningly easy for the squadron to be spotted as six white stripes on the pristine blue Arabian sea by a Pakistani aircraft (As a matter of fact, a Pakistani patrol aircraft did indeed notice ‘unidentified ships traveling north-west’.)

2100 hrs: A few faraway targets had started appearing on the radars of Corvettes (due to anomalous propagation – periodic but unique atmospheric conditions of Arabian Sea between Gujarat coast and Karachi, which allows electromagnetic waves to travel longer distances in a recognisable form), but were not attacked as they were not considered worthy of wasting missiles on. The squadron simply changed course briefly to avoid them.

2145 hrs: The distance to Karachi was now 80km. The squadron had a stroke of good luck. Pakistani Navy had commanded all non-navy ships to stay out of the Karachi harbour at a range of minimum 112km between dusk and dawn. So any beacon identified on the radars of the killer squadron could be safely predicted to be a Pakistani warship. Final checks on equipment in all vessels were performed. The radars were constantly being monitored on all ships (INS Poshak stayed behind in Mangrol and INS Vidyut stayed outside Karachi harbour to act as a mobile refueling depot and armed backup respectively.).

Attacking Pakistani Ships

2200 hrs: The radar in INS Nipat started beeping, showing two enemy targets. The first was 45 miles north-west, and the second 42 miles north-east. An excited commander B B Yadav quickly broke the radio silence and informed rear admiral Kuruvilla. Operation Trident had reached its most crucial leg.

Karachi harbour was now 35km away.

The first target on the radar, now around 27 km away, had started moving towards the missile boat. It was the Pakistani destroyer PNS Khaibar, originally HMS Cadiz of the UK Royal Navy, acquired by Pakistan in 1956. It was a huge vessel, weighing 3,290 tonnes when fully loaded. INS Nirghat and INS Kiltan were instructed to deal with the oncoming threat.

2245 hrs (PST): INS Nirghat moved swiftly, locking on the target and launching its first Styx missile. The missile took off towards the sky in the shape of a bright light, and then zoomed down towards PNS Khaibar. Khaibar mistook the missile for an aircraft diving in and started firing its Bofors anti-aircraft guns. The missile struck Khaibar on the starboard side below water level. The ship instantly lost propulsion, plunged into darkness and huge flames shot up due to an explosion in the boiler room. Khaibar started slumping towards the side of the explosion and sent an SOS to naval headquarters: “Enemy aircraft attacked in position 020 FF 20. No 1 Boiler hit. Ship stopped.”