India will become the third-biggest economy in the world by 2030. Stating this at the convocation of the 125th course of the National DefenceAcademy at Khadakwasla in Pune, Deputy Chairman of the Planning Commission Montek Singh Ahluwalia today said that by the year 2030, China will be number one, the US will be number two and India will be have the third-largest GDP in the world. He said that the challenge of the defence forces is to defend and protect the interests of the nation that will have the third-largest GDP in 17 years. He also said that when the size of the economy increases, the challenge also increases. India, with a GDP of 1.84 trillion US Dollar, was ranked the 10th-largest economy in 2012, according to the World Bank. The US, at 15.6 trillion dolar, is the largest economy.