Buenos Aires, Argentina—An Argentine submarine is missing at sea.

ARA San Juan (S-42) was last heard off two days ago.  Since then, the 44-crew submarine has failed to respond to the Argentine military’s repeated communication attempts.

“We are investigating the reasons for the lack of communication. If there was a communication problem, the boat would have to come to the surface,” said Enrique Balbi, a navy spokesperson.

The submarine was heading from the city of Ushuaia, southern Argentina, to her home port in Mar del Plata, 1,800-miles to the north.

The search-and-rescue units are concentrating their efforts in the San Jorge Gulf, in the southern Atlantic coast of Argentina.

They include Argentine navy destroyers, corvettes, and S-2E Tracker surveillance aircraft.

A NASA P-3 Orion anti-submarine and surveillance plane stationed in Patagonia has joined the rescue efforts.

The United Kingdom has offered the Argentine military the assistance of an RAF C-130 from the nearby Falkland Islands.