ARA San Juan (S-42)
Between 1924 and 1955, France administered the islands as a dependency of Madagascar. In 1938, the Crozet Islands were declared a nature reserve. The Crozet Islands became part of the French Southern Territories in 1955. In 1961, a first research station was set up, but it was not until 1963 that the permanent station Alfred Faure opened at Port Alfred on Île de la Possession (both named after the first leader of the station). The station is staffed by 18 to 30 people (varying by season). They perform meteorological, biological, and geological research, and maintain a seismograph and a geomagnetic observatory. The comprehensive Nuclear Test Ban Treaty Organization has listening equipment on the island and it was disclosed that two of its stations, the other being on Ascension Island, detected what is believed to be an underwater, non-nuclear explosion off the coast of Argentina and believed to be the fatal accident of the ARA San Juan submarine in 2017..
Alfred Faure opened at Port Alfred on Île de la Possession
Argentine Navy spokesman Captain Jorge Balbi presented close-up photos of the wreck in a press briefing. The pictures show the imploded pressure hull, with the bow section, sail and propellers scattered in an area of 8,000 square metres (86,000 sq ft).
ARA San Juan (S-42) was a TR-1700-class diesel-electric submarine in service with the Submarine Force of the Argentine Navy from 1986 to 2017. It was built in West Germany, entering service on 19th November 1985, and underwent a mid-life update from 2008 to 2013. On 15 November 2017, San Juan went missing during a routine patrol in the South Atlantic off the coast of Argentina, believed to have suffered an electrical malfunction, and a multi-nation search operation was mounted. Within hours of San Juan's last transmission, an acoustic anomaly consistent with an implosion was detected in the vicinity of the vessel's last known location. On 30 November, the search and rescue operation was abandoned. The Argentine Navy reported on 16th November 2018 that the wreck of San Juan had been found at a depth of 907 metres (2,976 ft), 460 kilometres (290 mi) southeast of Comodoro Rivadavia. The submarine's imploded wreckage was strewn over an area of 8,000 square metres (86,000 sq ft). On 27 November, it was revealed to the press that according to the submarine's last report from 15 November, San Juan's snorkel had leaked water into the forward storage batteries the day before, which ignited a fire. After quenching the fire, the crew disconnected the forward batteries. The submarine continued to move powered by the aft batteries. It had been considered that the probability of locating the wreck in the area where it was eventually found was 90%, but previous searches failed to find it due to insufficient technology and presence of numerous submarine canyons..
The Vela incident, also known as the South Atlantic Flash, was an unidentified double flash of light detected by an American Vela Hotel satellite on 22 September 1979 near the Prince Edward Islands in the Indian Ocean. The cause of the flash remains officially unknown, and some information about the event remains classified by the U.S. government. While it has been suggested that the signal could have been caused by a meteoroid hitting the satellite, the previous 41 double flashes detected by the Vela satellites were caused by nuclear weapons tests. Today, most independent researchers believe that the 1979 flash was caused by a nuclear explosion, perhaps an undeclared joint nuclear test carried out by South Africa and Israel. Since the "double flash", if one existed, could have occurred not very far to the west of the French-owned Kerguelen Islands, it was a possibility that France was testing a small neutron bomb or other small tactical nuclear bomb. The satellite reported a double flash, which could be characteristic of an atmospheric nuclear explosion of two to three kilotons, in the Indian Ocean between the Crozet Islands (a sparsely inhabited French possession) and the Prince Edward Islands (which belong to South Africa) at 47°S 40°E. It was reported that low levels of iodine-131 (a short-half-life product of nuclear fission) were detected in sheep in the southeastern Australian States of Victoria and Tasmania soon after the event. Sheep in New Zealand showed no such trace. The Arecibo Observatory in Puerto Rico detected an anomalous ionospheric wave during the morning of 22 September 1979, which moved from the southeast to the northwest, an event that had not been observed previously.
After the event was made public, the United States Department of Defense (DOD) clarified that it was either a bomb blast or a combination of natural phenomena, such as lightning, a meteor, or a glint from the Sun. The initial assessment by the United States National Security Council (NSC), with technical support by the Naval Research Laboratory in October 1979 was that the American intelligence community had "high confidence" that the event was a low-yield nuclear explosion, although no radioactive debris had been detected, and there were "no corroborating seismic or hydro-acoustic data. A later NSC report revised this position to "inconclusive" about whether a nuclear test had occurred. That same report concluded that if a nuclear test had been carried out, responsibility should be ascribed to the Republic of South Africa. If a nuclear explosion did occur, it occurred within the 3,000-mile-wide (4,800 km diameter) circle covering parts of the Indian Ocean, the South Atlantic, the southern tip of Africa, and a small part of Antarctica. The explosion was picked up by a pair of sensors on only one of the several Vela satellites; other similar satellites were looking at different parts of the Earth, or weather conditions precluded them seeing the same event. The Vela satellites had previously detected 41 atmospheric tests—by countries such as France and the People's Republic of China—each of which was subsequently confirmed by other means, including testing for radioactive fallout. The absence of any such corroboration of a nuclear origin for the Vela incident also suggested that the "double flash" signal was a spurious "zoo" signal of unknown origin, possibly caused by the impact of a micrometeoroid. Such "zoo" signals which mimicked nuclear explosions had been received several times earlier.
Israel
Long before the incident, US intelligence suggested Israel had nuclear weapons. Furthermore, independent investigations differently conducted by authors Seymour Hersh, Leonard Weiss, Thomas C. Reed, and Richard Rhodes suggested that Israel had cooperated with South Africa to test a nuclear weapon with the knowledge and protection of Carter’s administration. Reed continues to claim that the incident was an Israeli neutron bomb that was meant to go undetected by testing it during a window of opportunity when no active vela satellite observed the area.
South Africa
The location of the incident was within South Africa’s territory and, at the time, the country had a nuclear weapons program. However, South Africa had ratified the Partial Test Ban Treaty and therefore had nothing to hide. After apartheid, South Africa disclosed all of its nuclear weapons information and it became a common consensus that at the time of the incident, the country had no capacity to construct such a bomb. Furthermore, two years before the incident, the UN Security Council Resolution had put an arms embargo against South Africa, requiring all states to refrain from "any co-operation with South Africa in the manufacture and development of nuclear weapons."
USSR
Other sources claimed that the Soviet Union might have been responsible for the incident to secretly violate the 1963 Partial Nuclear Test Ban Treaty. Proponents of this claim cite the USSR’ 1959 secret underwater tests.
India
In 1974, India conducted the Smiling Buddha nuclear test. Although India’s test was legal, the country became a suspect because it was capable and its navy frequented the region.
The IRR-2 research reactor at the Negev Nuclear Research Center
Israel is widely believed to possess nuclear weapons, though the country neither acknowledges nor denies the existence of a nuclear arsenal. Israel is not a party to the Nuclear Non-Proliferation Treaty (NPT) and has not accepted IAEA safeguards on some of its principle nuclear activities. Their policy of nuclear opacity has been generally tolerated by both allies and adversaries. Most estimates posit that Israel possesses about 90 plutonium-based nuclear warheads and has produced enough plutonium for 100-200 weapons. These estimates have been fairly consistent for decades, which points to a nuclear posture defined by Israel’s deterrence needs. Israel appears focused strictly on survival and does not seek to threaten other nuclear-armed states. It is widely believed that the plutonium for Israel’s nuclear weapons program was produced by a reactor built with French assistance. The IRR-2 research reactor at the Negev Nuclear Research Center is commonly referred to by the city that hosts it, Dimona. It is officially a 26-megawatt thermal reactor, but some believe that is an underestimation of its capacity. The facility is not under IAEA safeguards. The IRR-2 went critical in December 1963 and likely helped Israel produce its first nuclear weapon in 1966-67, although these reports have not been officially confirmed. The declassification of sensitive government documents show that at least by 1975 the U.S. government was convinced Israel had nuclear weapons. The lack of clarity surrounding an Israeli nuclear weapons program is a key obstacle to establishing a weapons of mass destruction free zone in the Middle East. The global pledge to create such a zone in 1995 was crucial to securing the indefinite extension of the NPT. The absence of the zone today presents a continuing challenge to this critical agreement.