Argentina's navy confirmed an unusual noise heard in the ocean near the last known position of an Argentine navy submarine appeared to be an explosion, dashing the last hopes of finding the vessel and its 44 crew members.
Concern for the missing submarine and its crew has gripped Argentina since it was reported overdue at its Mar del Plata base on November 17, two days after the explosion.
"An anomalous, singular, short, violent and non-nuclear event consistent with an explosion," occurred shortly after the submarine's last communication, navy spokesman Captain Enrique Baldi told a news conference in Buenos Aires on Thursday.
After days of false hopes, families of the crew members keeping vigil at the base reacted angrily to the news, saying the navy had lied to them over the past week.
"I feel cheated," Itati Leguizamon, whose husband was on the San Juan, said.
Police and soldiers form a protective circle around distraught relatives of missing submarine crew member Celso Oscar Vallejo (AAP) Source: AAP
"They are perverse. They are miserable.
"They did not tell us they died. But they tell us they are three thousand meters (9,800 feet) deep," Ms Leguizamon added as other family members shouted angrily around her.
"People are becoming very aggressive. They lied to us."
Underwater sounds detected in the first days of the search by two Argentine search ships were determined to originate from a sea creature, not the vessel. Satellite signals were also determined to be false alarms.
Russia was the latest navy to volunteer to a multinational sea search, sending an oceanographic research ship as the operation shifted focus from rescue to recovery.
The Russian defence ministry said the Yantar was steaming to the area from the western coast of Africa on the orders of President Vladimir Putin.
The week-long search has focused on the sub's last known position, about 320 kilometres off the Argentine coast, but has been hampered by bad weather.
The San Juan, a 34-year-old German-built diesel-electric submarine, had reported a battery problem on November 15 and said it was diverting to its home base at Mar del Plata, but did not send a distress signal, according to the navy.
Mr Balbi had admitted on Wednesday the situation for the sub and its crew appeared to be worsening.
But he refused to speculate at that point on the origin of what he initially described as a "hydro-acoustic anomaly", detected in the ocean almost three hours after the sub's communication and 48 kilometres north of its last known position.
Mr Balbi explained that information about the unusual noise only became available Wednesday after being relayed by the United States, and "after all the information from all agencies reporting such hydroacoustic events was reviewed".
A former submarine commander told AFP a problem with batteries, as the sub had reported, could cause an explosion.
"A severe problem with batteries might generate hydrogen. Hydrogen above a certain percentage is explosive," the commander, who requested anonymity, said.
"It explodes by itself. Should they have had an explosion, then what? Everything was lost."
The ARA San Juan would have had enough oxygen for its crew to survive underwater in the South Atlantic for seven days since its last contact, according to officials. That time had elapsed by 0730 GMT Wednesday.
Putin phone call
Argentina is leading an air-and-sea search with help from several countries now including Brazil, Britain, Chile, Colombia, France, Germany, Peru, Russia, the United States and Uruguay.
Mr Putin offered "words of support over the situation with the San Juan submarine" in a phone call to Argentine President Mauricio Macri late on Wednesday, the Kremlin said.
US President Donald Trump offered his support, tweeting: "May God be with them and the people of Argentina!"
Russia said the Yantar "is equipped with two deep water submersibles which allow exploratory searches at a depth of up to 6,000 meters."
The conditions had fueled hopes that the vessel may have been on the surface undetected.
Despite mechanical problems, the crew could survive indefinitely if the sub retained the ability to rise to the surface to "snort" or replenish its air.
Relatives' vigil
About 100 family members had been waiting hopefully inside the Mar del Plata naval base, the perimeter fence of which is festooned with messages of encouragement for the crew, religious images and Argentine flags and banners.
Families of the crew, some from distant parts of Argentina, have been keeping vigil here since a multinational air and sea search began last Thursday.
Ms Leguizamon described how navy officers broke the news of the explosion to the families.
"They asked most of the people to leave and just close family members to stay," she said.
"When they heard the news they all exploded in there, they jumped on them and they had to stop reading their statement. People became very aggressive.
"They are going to continue looking for it, because they have an obligation to do so.
"They launched a search because it looks good, because they sent shit out there to sail.
"They already had problems in 2014, because it couldn't surface. Now I don't care if everything is known, he's not here anymore," she said, referring to her husband.
The German-built submarine was launched in 1983 and underwent a refit to extend its life from 2007-2014.
Suarez, she said, "was prepared for death. He always went to confession and was at peace. He was ready."
'They're all dead'
"I've just learned that I'm a widow," Jessica Gopar, wife of Fernando Santilli - an electrician aboard the sub, before bursting into tears.
After hearing the news of an explosion on board, her first reaction was, "They're all dead. It's the first thing I thought".
"We are going to get together and ensure we are going to get justice. I don't need a plaque that says 'the heroes of the San Juan'," she said before collapsing in tears.
"He was my great love, we were going out for seven years, married for six, 13 years together and now we have a son, Stefano.
"How do I tell my son that he is left without a father," Ms Gopar, who on Wednesday posted an emotional Facebook message to her husband saying that her one-year old had just learned to say "Dad", said.
Julian Colihuinca, 19, was at the perimeter fence, pinning up a plastic banner on which he had scrawled, "Be strong, the families of the 44".
"I'm the son of a tactical diver. The tragedy hits close," she said.
"I know all the crew by their faces."
Outside the base, Hugo Daniel, 43, stopped as he was passing by on his bicycle.
Like the rest of the nation, he had been following the unfolding tragedy over the past week.
"It's a tragedy that will go down in history," he said.
"Machines fail. The people who were on the submarine knew the risks."
Referring to the strained relationship between many Argentines and their military, he said that during the 1976-83 dictatorship "they used to torture people here," pointing to a plaque on the fence that notes it was once a "clandestine detentionr centre".
