Theatre Level Operational Readiness Exercise (TROPEX) is an inter-service military exercise involving the participation of the Indian Army, Air Force, Navy and the Coast Guard. The exercise generally commences at the beginning of each year and lasts a month. It is generally carried out in three phrases: independent workup phase, joint workup phase and tactical phase. The exercise is designed to test the combat readiness of the Indian naval units, as well as the Indian Air Force, Indian Army and the Indian Coast Guard. It also seeks to strengthen interoperability and joint operations in a complex environment. Beginning in 2005, the exercise has been held annually, with the exception of 2016 and 2018. The last edition of the exercise was conducted in 2021. History TROPEX 2005 TROPEX 2005 was conducted by the Indian Navy's Western Naval Command off the Goa coast. It commenced in April 2005 and involved units of the Indian Navy, Army, Air Force and Coast Guard. The exercise included weapon firings and evaluation of various combat tactics. Vice Admiral Madanjit Singh, Flag Officer Commanding in Chief (FOC-in-C) Western Naval Command, witnessed the exercise. TROPEX 2006 TROPEX 2006 commenced on 5 April 2006 and continued until 26 April 2006. The exercise was conducted off the western seaboard of India. It included a joint workup phase from 5 to 11 April, comprising both fleets. This was followed by a deployment and tactical phase which commenced on 12 April and continued until 21 April 2006. On 21 April 2006, an Indian naval missile corvette Prahar, collided with a merchant vessel Rajiv Gandhi head-on and sank about three hours after the collision about ten nautical miles off Mormugao port in Goa. The corvette was on its way to Mumbai, after the completion of TROPEX exercise, when the incident happened. The corvette's entire crew of seventy-three were rescued before it sank and no injuries were reported. TROPEX 2007 TROPEX 2007 commenced on 30 January 2007 and was conducted in the Arabian Sea. The exercise involved fifty ships from the Indian Navy's Western and Eastern Naval Command, including the aircraft carrier , and s, and , and s. It also involved elements from the Army, Air Force, and the Coast Guard. Towards the later stages of the exercise, the navy deployed UAVs, Kamov 31 AEW helicopters, missile defence systems like Barak, Shtil and Kashmir surface-to-air missiles, besides land-attack missiles. During the exercise, participating