on 3 june 2011, saab announced that it was awarded a contract for the upgrading of the two naresuan class frigates. the scope of the upgrade will include saab's 9lv mk4 combat management system, sea giraffe amb, ceros 200 fire control radar, eos 500 electro-optics system and data link systems for communications with the newly acquired royal thai air force erieye surveillance aircraft.