In the early 1980s, a series of submarine incidents occurred within Swedish territorial waters, the most famous of which was U 137 which ran aground outside Karlskrona in 1981.

The decision was to use the Ytattack-81 project and modify it for ASW operations, as designing a completely new ship is a time-consuming and costly task.

In the middle of the 1990s, the ships started to show their age, mainly because of their high mileage and the latest few year's explosive development of electronics.

Much of the modification was also made with low maintenance in mind to minimise the need for expensive repairs in the future.

In early 2009 the Swedish government decided that the two ships in the class were to join the EU-led taskforce outside Somalia, where it would fight piracy.