As I write, police in the Indian state of Orissa are searching for the bodies of their comrades in a mountain reservoir. The dead are among 37 members of an elite counter-insurgency unit missing after Maoist rebels strafed and sank a police launch. Hundreds of police and paramilitary troops supported by helicopters are now combing the surrounding forests for the guerillas who carried out the attack. It could be a scene from any one of a dozen films set during the Vietnam or Algerian wars. But it is a slice of real life in a large swathe of India that little resembles the shining, modernising, booming, English-speaking entity celebrated by magazine cover stories and books with titles such as Planet India and Think India.

India has battled separatist insurgencies ever since independence in 1947, with parts of the country’s periphery under some form of military occupation on an almost continuous basis. Only rarely have these savage little conflicts, with their cruel cycle of rebellion and repression, made international headlines or affected the benign image of India so skilfully burnished by the post-independence elite. But the Maoist insurgency may represent something different and much more dangerous to the republic.

Unlike the long-running rebellions in north-eastern states such as Assam and Nagaland, it is not confined to a border area or limited to a particular, ethnically distinct group. On the contrary, the Maoists have a significant presence in 14 out of India’s 28 states. Moreover, the insurgency has grown without the benefit of sanctuaries or training camps in neighbouring countries, and its successes cannot plausibly be attributed to the secret agents of Pakistan or any other foreign hand. And though India’s democracy has long proved its resilience, even in the face of appalling terrorist attacks and political assassinations, it is possible that the Maoist revolt could genuinely threaten the economic basis of the new India.

The sinking of the police launch in Orissa is the first major attack by the Communist Party of India (Maoist) – formerly the People’s War Group and the Maoist Communist Centre – since their comrades in Nepal achieved an electoral triumph this spring. It’s arguably their most daring operation since December, when Maoist guerillas broke 300 prisoners out of jail in the state of Chhattisgarh. It may be the most successful since March 2007, when uniformed and well-armed cadres stormed a police post in the same state, killing 55 members of the security forces, at no loss to themselves. In recent years there have been many smaller outrages including successful assaults on a police training academy near the state capital of Orissa, the assassination of a federal MP at a football match and the seizure of a passenger train for 12 hours in Jharkhand.