India's government says Maoist rebels represent the country's greatest internal security threat.

They have waged war against the government for more than 40 years. More than 6,000 people have been killed, and many more maimed and injured.

At least 50,000 federal paramilitaries are fighting the insurgents. That figure sits alongside police and special government task forces, all at huge financial cost.

In the last four years, almost $30 million in extra defence money has gone to states where Naxals have the heaviest presence.

But this expensive strategy appears to be getting the government nowhere.

In our exclusive report on the Naxal movement, Al Jazeera's Kamal Kumar discovers the dangers of policing the front line.