Unit/ Formation: SBS
Location: Europe and Gibraltar
Period/ Conflict: The Falklands War
Date/s: June 1982
The French AM 39 Exocet: an air-launched, sea-skimming, anti-ship missile deployed by Argentina against the British during the Falklands campaign in 1982. This missile was a clear danger to the Task Force aircraft carriers, the loss of just one of which would have seriously prejudiced the outcome. By its mere presence the Exocet affected much of the strategic and tactical thinking of the British commanders at sea and in the United Kingdom.
There are at least three un-tabulated special forces operations, PLUM DUFF, MIKADO and KETTLEDRUM, that were tasked to destroy Argentina’s Exocet missiles during the 1982 Falkland’s campaign all planned to be conducted in South America. 
Aerospatiale AM-39 Exocet
Powerplant: A solid-propellant rocket engine
Dimensions: Wingspan 3ft (1.1m), length 15ft (4.7m)
Performance: Max range 31 miles (50km) at sea level, 43.5 miles when launched at 32,800ft, max speed 715mph or approx Mach 0.93
Summary: Development began in 1967. The 1968 ship-launched MM38 was developed into an air-launched version – first as AM-38 and later as AM-39. First delivered to the French navy in 1979, missiles were sold to Argentina two years later.
The weapon was autonomous, receiving target information from the aircraft and using its own radar to update the target position on the last part of its flight. It also had an inertial navigation system. With a launch weight of 1,477lb, it contained a 372lb high-explosive fragmentation warhead.
Argentine Navy Dassault-Breguet Super Étendard warplanes carrying the AM39 air-launched version of the Exocet caused damage which sank the Royal Navy destroyer HMS Sheffield on 4 May 1982. Two more Exocets struck the 15,000-ton merchant ship Atlantic Conveyor on 25 May.
Two MM38 ship-to-ship missiles were removed from the destroyer ARA Seguí, a former US NavyA llen M. Sumner-class destroyer, and transferred to an improvised launcher for land use. The missiles were launched on 12 June 1982 and one hit the destroyer HMS Glamorgan.
In the years after the Falklands War, it was revealed that the British government and the Secret Intelligence Service (MI6) had been extremely concerned at the time by the perceived inadequacy of the Royal Navy's anti-missile defences against the Exocet and its potential to tip the naval war decisively in favour of the Argentine forces. A scenario was envisioned in which one or both of the force's two aircraft carriers (Invincible and Hermes) were destroyed or incapacitated by Exocet attacks, which would make recapturing the Falklands much more difficult.
Actions were taken to contain the Exocet threat. A major intelligence operation was initiated to prevent the Argentine Navy from acquiring more of the weapons on the international market.
The operation included British intelligence agents claiming to be arms dealers able to supply large numbers of Exocets to Argentina, who diverted Argentina from pursuing sources which could genuinely supply a few missiles. France denied deliveries of Exocet AM39s purchased by Peru to avoid the possibility that Peru might supply them to Argentina because they knew that payment would be made with credit from the Central Bank of Peru. British intelligence had detected the guarantee was a deposit of two hundred million dollars from the Andean Lima Bank, an owned subsidiary of the Italian Banco Ambrosiano. 
When MI6 discovered that a shipment of Exocets bound for Argentina were onboard a cargo ship moored in a foreign harbor, the SBS were tasked with destroying it. SBS divers were to swim into the harbor and place limpet mines on the ship's hull with the aim of sinking it.
The operation was postponed at the last minute so as not to cause an incident in a European harbour the launch point was moved to Gibraltar.
The mission was apparently called off at the last minute when it looked as if the campaign on the islands was drawing to a close and it was calculated that the missiles would not reach Argentina in time to be of help to the Argentinean's. 
 Exocet Falklands: The Untold Story of Special Forces Operations - Ewen Southby-Tailyour (Tells a revelatory account of three un-tabulated special forces operations, PLUM DUFF, MIKADO and KETTLEDRUM, that were tasked to destroy Argentina’s Exocet missiles during the 1982 Falkland’s campaign)
 As described by ex-SBS operator Duncan Falconer's memoirs, 'First into action'