The U.S. Navy announced Friday it will deploy its  http://www.southcom.mil/News/PressReleases/Article/1376328/release-us-navy-p-8a-poseidon-to-support-argentina-search-for-submarine/" rel="nofollow - P-8A Poseidon maritime aircraft  to assist in the search for the ARA San Juan, a missing Argentine submarine with 44 crew members aboard. The submarine was last heard from Wednesday from the southern Argentine sea, 268 miles from the Patagonian coast. It was headed to the coastal city of Mar del Plata in Buenos Aires province, Reuters reported. Navy spokesman Enrique Balbi told Reuters the operation was officially upgraded to search-and-rescue status Friday. But poor weather conditions have made it difficult for the Navy to locate the missing vessel, Reuters reported. The P-8A Poseidon is expected to aid in the search because its technology allows it “to support a wide range of missions over large bodies of water, including sub-surface search-and-rescue operations,” a Navy statement said. The U.S. also has offered to fly the NASA P-3 explorer aircraft to help in the search, Reuters reported. Other countries offering assistance include include Brazil, Uruguay, Chile, Peru, Britain and South Africa. "We share their concern and that of all Argentines," President Mauricio Macri tweeted, according to Reuters. "We are committed to using all national and international resources necessary to find the ARA San Juan submarine as soon as possible."

Hope grew Saturday night that the crew of Argentina’s missing submarine, the ARA San Juan, might still be alive. Argentina's navy said it detected seven brief satellite calls late Saturday that officials believe may have come from the submarine, with 44 crew members aboard, that hasn't been heard from since Wednesday. The communication attempts "indicate that the crew is trying to re-establish contact, so we are working to locate the source of the emissions," the navy said on its Twitter account. "The calls of a short duration, between 4 and 36 seconds, were received between 10:52 and 10:42 on Saturday at different bases." But Argentine authorities cautioned that it has not been confirmed the calls came from the submarine, though that is the working hypothesis.

A multinational search intensified on Tuesday for Argentina’s missing submarine with 44 crew members off the country’s coast, as the clock may be ticking on the crew’s oxygen supply. The German-built San Juan submarine has been missing since Wednesday, when it reported a battery failure and lost contact with the Argentine Navy. Two Argentine Navy ships detected signals a day ago from about 220 miles off the coast at a depth of 650 feet, but the source of the signals could not be determined,  http://www.bbc.com/news/world-latin-america-42045380" rel="nofollow - the BBC reported .  “Some sources were saying that this was banging on the hull in Morse code signals,” Enrique Balbi, a navy spokesman, said. He said the sources could not be verified. The submarine reportedly carried enough food, oxygen and fuel for the crew to survive about 90 days on the sea’s surface, but only enough oxygen to last seven days underwater, he said. The submarine was originally scheduled to arrive Sunday in Mar del Plata, a navy base about 250 miles southeast of Buenos Aires. A U.S. Navy P-8 Poseidon aircraft assisted in the search efforts by deploying its first aircraft on November 18 and a second ship with special tracking equipment and deep-sea rescue modules on November 20,  http://www.af.mil/News/Article-Display/Article/1376901/mobility-aircraft-deliver-us-navys-undersea-rescue-capabilities-to-argentina/" rel="nofollow - the US Air Force stated . Argentine President Mauricio Macri met with family members at the base as they waited for news about their loved ones. Concerned family members have taken to social media to plead for help in the search process. “Pray so that my husband, Fernando Santilli, can return home,” Jessica Gopar wrote on  https://twitter.com/JEKOGOPAR/status/932346460024303617" rel="nofollow - Twitter . “He’s in the San Juan submarine." More than a dozen international vessels and aircraft have joined the search for the missing submarine, which has been set back by stormy weather that has caused waves up to 20 feet.  Eleven boats and 10 planes from Argentina, Brazil, Chile, Peru, South Africa, Uruguay and the UK were assisting in the search as well, Balbi said.