A multi-nation search operation was mounted to try to locate the submarine which was believed to have suffered an electrical malfunction.
It has now been revealed by the Argentinian Navy that they believe the submarine may have exploded, killing all 44 crew.
Experts say even if the ARA San Juan is intact, its crew might have had only enough oxygen to last seven to 7 days. The German-built diesel-electric sub went missing as it sailed from the extreme southern port of Ushuaia to the city of Mar del Plata, about 250 miles southeast of Buenos Aires.
Argentine Navy spokesman Enrique Balbi said evidence showed “an anomalous event that was singular, short, violent and non-nuclear that was consistent with an explosion.”
“According to this report, there was an explosion,” Mr Balbi told reporters.
“We don’t know what caused an explosion of these characteristics at this site on this date.”
On the 22nd of November, the Argentine Navy investigated a “hydroacoustic anomaly” identified on the 15th of November, three hours after the last contact of the lost submarine; ships and airplanes were sent back to the last contact point with ARA San Juan.
During a search flight over the South Atlantic, a US P-8A Poseidon aircraft detected an object near the area where the missing submarine sent its last signal. The plane returned to its base in Bahía Blanca late the same day.
Yesterday the Argentine Navy said an event consistent with an explosion had been detected on the day the submarine lost communications by CTBTO seismic anomaly listening posts on Ascension Island and Crozet Islands. The Navy received information through the Argentine ambassador in Austria since the CTBTO is based in Vienna.
The organisation had been asked to analyse data in the search area by the Argentine government on the week of the disappearance, but no leads surfaced until the 22nd of November when the CTBTO informed the government.