A man stands in front of signs in support of the 44 crew members of the ARA San Juan submarine missing at sea, placed on a fence outside the Argentine Naval Base where the submarine sailed from, in Mar del Plata, Argentina November 20, 2017. REUTERS/Marcos Brindicci

A man stands in front of signs in support of the 44 crew members of the ARA San Juan submarine missing at sea, placed on a fence outside the Argentine Naval Base where the submarine sailed from, in Mar del Plata, Argentina November 20, 2017. REUTERS/Marcos Brindicci