NEW DELHI: In the midst of evolving security situation in the region, India and Russia will hold a mega war game in October involving their armies, navies and the air forces for the first time to further ramp up military ties.The exercise Indra , which will be held in Russia from October 19 to 29, will primarily focus on achieving coordination between forces of the two countries in a tri-services integrated theatre command scenario, military sources said.It will be for the first time India will participate in a tri-services exercise with a foreign country with such a large scale participation by the Navy, the Army and the Air Force , they said.A total of 350 Indian Army personnel will participate at the mega exercise and the contingent will be led by a major- general rank official. The contingents by the Navy and the IAF will also be sizeable in numbers, the sources said.The exercise is taking place at a time when India's ties with China have nosedived due to the simmering border dispute and its ties with Pakistan have deteriorated over cross-border terrorism and number of other issues.The sources said the exercise will take place in three locations in Russia including in mountainous Vladivostok region.The armies, navies and air forces of Russia are holding bilateral exercises separately but this is for the first time, both the countries will carry out a tri-services exercise.Russia has been a long-standing defence partner of India and both the countries are now eyeing to further deepen the ties.During Prime Minister Narendra Modi's visit to Russia in June, both countries had decided to "upgrade and intensify" defence cooperation through joint manufacture, co-production and co-development of key military hardware and equipment.A vision document, issued then had said that both the countries also decided to work towards a qualitatively higher level of military-to-military cooperation.India has already decided to significantly ramp up its defence capability and has lined up billions of dollars of procurement proposals as part of military modernisation.The armies, navies and air forces of Russia are holding bilateral exercises separately but this is for the first time, both the countries will carry out a tri-services exercise.