Aguad said during an interview Monday on an Argentine television news program that international nuclear agencies detected what appeared to be a explosion near the last known location of the ARA San Juan when it disappeared November 15. The extreme conditions and passage of time likely means the sub's crew did not survive.
"You mean they're all dead?" the interviewer asked.
"Exactly," Aguad said.
Unmanned submarines from the United States and Russia will search depths of up to 6,000 meters, or 19,685 feet, in what the defense minister called an inverted mountain range in the South Atlantic for signs of the submarine, which disappeared a few hundred kilometers off Argentina's coast.
The Argentine military has said the vessel first reported a battery short-circuit roughly 10 hours before an explosion-like sound was detected near the sub's last known location.
Naval officials have said there was no chance of survival for the crew. They called off the rescue operation last week and shifted focus to recovering the wayward vessel.
Aguad also said the submarine's maintenance may have been compromised, but added that the claims had yet to be investigated.
"We don't have clear evidence but there are suspicions that point to corruption," Aguad said, adding that repairs on the vessel that were supposed to take two years instead took five years.
In addition, audits show some parts and materials used in the repairs were not up to standard, he said. There also were suspicions of cost overruns, the defense minister said.
The ARA San Juan disappeared about midway on its journey from Ushuaia in the country's south and its northern port of Mar del Plata. At the height of the search, 28 ships and nine airplanes from 11 nations -- including the United States and United Kingdom -- scoured a roughly 40,000-square-kilometer area of the sea, backed by more than 4,000 people.
When it became clear the submarine had met with trouble, relatives of those on board gathered outside the Mar del Plata navy base, where many of the submariners were based.
For weeks, they pushed for answers, relying on updates from the Argentine navy for a glimmer of hope that their relatives may have survived.
Local school children attached messages to the fence around the base, praying for those on board, as the entire country waited for news.
The navy's announcement last week that there was no chance of survival for the crew shocked and angered submariners' relatives, including some who fainted or needed medical attention upon hearing the news, Susana Alvarez, a friend of one of the missing officers, told state-run news agency Télam.