Dumping of munitions at sea has been prohibited since the 1972 London Convention on the Prevention of Marine Pollution by Dumping of Wastes and other Matter came into force in 1975, later completed by the 1996 Protocol which specifically prohibits all dumping of munitions
As a signatory to the convention and protocol, France however reserved the right to dump munitions which “cannot be disposed of on land without presenting severe risks for man and the environment”.
It appears that the French Navy has stopped all dumping of munitions at sea since the blast involving the barge La Fidèle, on 30 April 1997, when preparing to dump grenades, killing 5 people.
The recovery of all dumped munitions is unthinkable: it would be both too costly and too risky. It would also require on land disposal facilities which do not currently exist.
In situ detonation raises the practical difficulty of isolating and individually treating munitions and that of controlling the explosion when they are grouped together.
On 22 July 1967, attempts to neutralise the cargo of munitions onboard the Polish vessel SS Kielce, sunk in waters 27 metres deep off Folkestone, resulted in a violent blast triggering panic across the nearby beaches.
Guidelines have been produced by several countries, for use by seamen, to help them to recognise the most dangerous munitions, heavily embedded or heavily degraded, and indicate what to do and what not to do.
In France, when a munition is brought aboard, fishermen are advised to alert the nearest semaphore or maritime rescue coordination centre, to secure it in place and to make their way to their port of registry, without entering it. An underwater mine countermeasures team is sent to meet them, to neutralise or detonate the munitions. A compensation system exists. However, often fishermen keep quiet, to save time, and throw the ammunition back into the sea in a non-trawlable area.