NEW DELHI: After Vietnam , Singapore and other countries in Southeast Asia, India is now also steadily stepping up military ties with Indonesia with an eye firmly on China. India and Indonesia have now decided to hold their first-ever joint air combat exercise as well as deepen maritime security cooperation.Defence sources say India also offered to train sailors from Indonesia in the complex art of submarine operations during the recent visit of defence secretary G Mohan Kumar to the country.Vietnamese sailors, incidentally, are already being trained in “comprehensive underwater combat operations’’ in the Indian Navy's submarine school INS Satavahana in Visakhapatnam. A similar programme to train the Vietnamese fighter pilots on Indian Sukhoi-30MKI fighter jets is set to begin this year, as was earlier reported by TOI.Much like the expansion of its military training, technology-sharing, joint exercises, visits and exchange of experts with Vietnam, India is now poised to crank up defence ties with Indonesia. Apart from exploring opportunities for collaboration in the defence production sector, the two countries will also upgrade their joint Army exercise called Garuda Shakti, the fourth edition of which was held at Magelang in Indonesia March 2016.The two navies have also been conducting coordinated patrols on their respective sides of the international maritime boundary line (IMBL) twice a year since 2002, with the aim to keep this vital part of the Indian Ocean region safe and secure for commercial shipping and international trade.As for Singapore, India has also renewed its air force training agreement with the city state for another five years. With land and airspace being a scarce commodity in Singapore, it has been utilising Indian military facilities to train its own small but high-tech armed forces under special agreements signed in 2007 and 2008.India, for instance, provides facilities to Singapore for exercises of mechanised forces at Babina and artillery at Deolali ranges as well as for fighters at the Kalaikunda airbase in West Bengal. The two countries also regularly hold the Simbex naval wargames, which have graduated from being purely anti-submarine warfare exercises to complex ones involving multiple facets of operations at sea.