Argentina is searching for a submarine that is lost contact with on Wednesday, though it has not yet declared it lost.
The San Juan, with a crew of 44, was returning to its base at Mar del Plata, 400km south of Buenos Aires, following a routine mission to Ushaia.
“We have not been able to find, or have visual or radar communication with the submarine,” navy spokesman Enrique Balbi said at a news conference.
The US, the UK and Chile have offered logistical and information support in the efforts to find the vehicle.
Argentina launched its own search on Thursday, with an air and sea search involving a destroyer and two corvettes.
The initial search was hampered “because it was carried out at night and in bad meteorological conditions prevailing in the area of operations,” according to Balbi.
The Argentine navy maintains that an issue with electronics and communication has caused this, and urged against speculation.
“We are praying to God and asking that all Argentines help us to pray that they keep navigating and that they can be found,” Claudio Rodriguez, the brother of one of the crewmembers, said on local TV channel Todo Noticias.