After a resounding general election win in May, India's Congress party-led government, no longer dependent on communist parties in its coalition, has decided to take on an estimated 22,000 Maoist rebels who hold sway over swathes of countryside. Operation “Green Hunt” reflects growing concerns in India that Maoists are becoming too strong after a decades-long insurgency. India's strong economic growth of the last few years did little to bring millions of poor villagers and tribals out of the poverty that helps act as the backbone of Maoist support. Here are a series of questions and answers about the Maoists and their growing threat in India. Who are the Maoists? They started an armed struggle with a peasant revolt in Naxalbari village in West Bengal state in 1967 but were initially crushed by the Congress-led government. After regrouping in the 1980s, they began recruiting hundreds of poor villagers, arming them with bows and arrows and even rifles snatched from police and government armouries. Indian authorities say they are led by Koteshwar Rao, alias Kishanji, who is in charge of militant activities, and Ganapati, the political leader. They remain hidden in dense forest bases and move around villages in remote areas. How big is the movement? The rebels have an estimated 22,000 combatants in more than 180 of the country's 630 districts, according to the government and the Institute for Conflict Management (IFCM), a New Delhi think-tank. They operate across a “red corridor” stretching from the southern state of Andhra Pradesh to the central state of Chhattisgarh and into West Bengal. They are in touch with other militant groups operating in India, including groups in Kashmir and the northeast, who help them. Police say they are equipped with automatic weapons, shoulder rocket launchers, mines and explosives. How big a threat are they to India's stability? Prime Minister Manmohan Singh has described the insurgency as the biggest internal security challenge since independence. More than 1,000 attacks were recorded last year, and the Maoists regularly attack railway lines and factories, aiming to cripple economic activity. Police believe they have started to make inroads into cities and other urban areas.