Indonesian Navy received the first batch of Turkey-made acoustic torpedo countermeasure jammers and decoys for its Nagapasa (Type 209/1400)-class diesel-electric submarines, a defense industry journal reported Friday.

The U.K.-based defense and security intelligence publisher Janes said in the report that the first batch of the acoustic decoy and jammers – ZOKA Decoy family – developed by leading Turkish defense firm ASELSAN arrived in the South Asian country on Oct. 22.

The ZOKA acoustic decoy and jammers developed and made available to the Turkish submarine fleet and Indonesia was the country that made the first overseas order for the system with a 2019 agreement.

The jammers work by emitting noises that saturate the acoustic operating frequencies of torpedoes, while the decoys can be programmed to simulate the acoustic and hydrographic characteristics of its host submarine.

ZOKA effectors are used in HIZIR Surface Torpedo Countermeasure System and ZARGANA Submarine Torpedo Counter Systems, and there are two different types of ZOKA effectors, deceptive and confusing, in both systems which were also developed by ASELSAN.