Answer : 3. "Bilateral military exercises"
Explanation :

Exercise VINBAX-2023 is a joint military exercise between India and Vietnam. The exercise aims to strengthen cooperation, promote interoperability and share best practices between the two countries. It also aims to strengthen military capabilities and cooperation for peacekeeping and defense initiatives. The fourth edition of the exercise is being held in Hanoi, Vietnam from December 11-21, 2023. A contingent of 45 Indian Armed Forces personnel are participating in the exercise.