sonar detectors were removed during the refit. The six corvettes form the Eighth Flotilla of the RSN. The Victory-class corvettes are projected to be replaced by six multi-role combat vessels by 2030, with the first ship to be delivered in 2025. Maritime security and response vessels The Sentinel-class maritime security and response vessels (MSRV) are four refurbished Fearless-class patrol vessels. The refurbishment plan was announced in March 2020 in response to the increase of sea robberies within the region, and foreign intrusions of Singapore territorial waters. As part of the refit, non-lethal LRAD and laser warning systems were added to increase operational flexibility, while fenders were incorporated into the hull to enable quicker alongside operations of suspicious vessels. The forward part of the bridge was also reinforced with ballistic-resistant armour. The first two vessels MSRV Sentinel and MSRV Guardian entered operational service on 26 January 2021, with the latter two MSRV Protector and MSRV Bastion on 20 January 2022. Other than the MSRVs, the flotilla will also operate two tugboats, and will operate new purpose-built vessels from 2026. The ships form the Maritime Security and Response Flotilla of the RSN. Historical fleet Missile gunboats The Sea Wolf-class missile gunboats were acquired in 1968 and based on the TNC 45 design from Fredrich Lürssen Werft. The first two gunboats—RSS Sea Wolf and RSS Sea Lion—were constructed in West Germany in 1972, while the remaining four were constructed locally by Singapore Shipbuilding and Engineering, with all six ships being commissioned by 1976. The gunboats were initially equipped with Israeli-manufactured anti-ship Gabriel missiles and Bofors guns. Sea Wolf fired the first missile by the RSN in March 1972. As new technology became available, a number of upgrading programmes were initiated to increase their strike capability and sophistication. Between 1986 and 1988, they were upgraded to launch Boeing Harpoon (SSM) surface-to-surface missiles, and in 1994, the Bofors gun was replaced with Mistral surface-to-air (SAM) missiles. The continuous upgrades to the gunboats' armaments and sensors made them regarded as being at the forefront of naval warfare technology between the 1980s and 1990s. The gunboats engaged in numerous exercises with foreign navies and visited many port of calls throughout their lifespan. On 13 May 2008, all six gunboats were retired at a sunset decommissioning ceremony held at Changi Naval Base following 33 years of service. Patrol vessels Between the 1970s and 1990s, the RSN operated and