these ships were recent and modern, they had been mostly equipped to operate in the support of low intensity conflicts in Africa, with limited installed capability for the anti-submarine and anti-ship roles. A planned fleet retrofit program, that included the installation of anti-ship and SAM missiles in the frigates and corvettes, could not proceed due to lack of funds. Without modernization, the Almirante Pereira da Silva-class frigates would soon be considered obsolete, being taken out of service in the early 1980s, but remaining moored at the Lisbon Naval Base until finally decommissioned in the early 1990s. With no significant new ships received for many years, the Portuguese Navy spent most of the 1980s, with four frigates, ten corvettes, three submarine and ten patrol ships, besides the support ships and minor units. The lack of specialized offshore patrol vessels, meant that the corvettes and even the frigates were intensively used for fishery protection and maritime search and rescue missions, besides their original military roles. Activity since 1990 Since 1990, the Portuguese Navy participated in various long-range missions where it has effectively conducted Portugal's foreign policy, using its units solely or integrated in vaster campaigns articulated with the Portuguese Army and the Portuguese Air Force. The Portuguese Navy has been especially active in peace-enforcement campaigns using combat ships, helicopter missions and special force marine detachments in amphibious and air evacuation of Portuguese nationals and other foreign civilians from dangerous war zones in Sub-Saharan Africa. The most notable missions performed were in Bolama (Guinea-Bissau, 1990), Luanda (Angola, 1992), and Bissau (Guinea-Bissau, 1998 and again in 1999). In these theatres the Portuguese Armed Forces set up secure zones amidst the combat areas, and evacuation units, sometimes operated by Portuguese Army special forces or Portuguese Marines Special Actions Detachment (DAE) to retrieve civilians from hot-spots and evacuate them onto frigates stationed off-shore or onto Portuguese Air Force C-130 Hercules transports, as in Angola in 1992. The Portuguese Navy has also actively participated in several international peace-keeping and peace-enforcing efforts in conjunction with other NATO, United Nations or European Union forces in numerous theatres, distant from Portuguese territory. In the 1990s, the Portuguese Navy is modernized with new vessels that include the s and the Portuguese designed and built s. The Navy's aviation is reborn with the reception of Westland Lynx helicopters. These new systems greatly increase the Navy's capacity to intervene in the high seas