The Agusta Westland AW101 is a medium/heavy-lift helicopter for military applications but also marketed for civil use. The helicopter was developed as a joint venture between Westland Helicopters in the UK & Agusta in Italy (now Agusta Westland). The aircraft is manufactured at the Agusta Westland factories in Yeovil, England & Vergiate, Italy. In spring 1977, the UK Ministry of Defence issued a requirement for an anti-submarine warfare (ASW) helicopter to replace the Royal Navy's Westland Sea Kings. Meanwhile, the Italian Navy was also seeking a replacement for its SH-3D/H, leading Agusta to discussions with Westland about the possibility of a joint development.