MUTSU BAY — Mineman 3rd Class Arturo Rivera from Tucson, Ariz., fires the expendable bathythermograph (BXT) into the water to read the expected sonar range of the day aboard mine countermeasures ship USS Pioneer (MCM 9) during Mine Warfare Exercise (MIWEX) 2JA 2020. MIWEX 2JA is an annual bilateral exercise held between the U.S. Navy and Japan Maritime Self Defense Force (JMSDF) to strengthen interoperability and increase proficiencies in mine countermeasure operations.