Washington: The US has approved the sale of 31 MQ-9B armed drones to India at an estimated cost of USD 3.99 billion, the American defence agency said. The drone deal was announced during Prime Minister Narendra Modi’s visit to Washington in June last year.Washington: The US has approved the sale of 31 MQ-9B armed drones to India at an estimated cost of USD 3.99 billion, the American defence agency said. The drone deal was announced during Prime Minister Narendra Modi’s visit to Washington in June last year.