Rapier is a British surface-to-air missile developed for the RAF Regiment and the British Army. Entering service in 1972, it eventually replaced all other anti-aircraft weapons in Army service; guns for low-altitude targets, and the Thunderbird (missile), used against longer-range and higher-altitude targets. It replaced Bofors guns and Tigercat missiles in RAF service. As the expected air threat moved from medium-altitude strategic missions to low-altitude strikes, the fast reaction time and high manoeuvrability of the Rapier made it more formidable than either of these weapons, replacing most of them by 1977. It remains the UK's primary air-defence weapon after almost 35 years of service, and its deployment is expected to continue until 2020.