 Three concentric rings of chain-link fence were erected in the city, and residents living inside were issued special passes to be permitted in to get to their homes.Ships belonging to the Argentine Navy were positioned offshore, while helicopters patrolled the beach area.The Argentine Air Force deployed A-4AR Fightinghawks to the nearest Tandil airbase supported by U.S. Air Force E-3 Sentry AWACS operating from Bahía Blanca.