The gunboat KASSOS (formerly known as PYRPOLITIS) is the first of her type, entirely of Greek design and construction. She was launched on 16 September 1992 with the sponsor Voula Patoulides, Olympic gold medalist of Barcelona.

She was activated at the Hellenic Shipyards SA (Skaramanga) on 4 May 1993 when the Greek flag was raised with Commander C. G. G. Karavitis P.N.

It has taken part in several national and inter-allied exercises and was the first ship to arrive in the area of Imia during the Greek-Turkish crisis in January 1996. It participated in the operation “Security Assistance for the 2004 Olympic Games”, in several search and rescue and preventive medicine operations.

On 11 November 2005 it was decided to rename the ship to K/F KASOSOS in order to honour the martyr island with its heroic inhabitants, an island located in the area where the ship operates.

The first Captain of the K/Φ KASOS was Commander K. Kyriakidis P.N.