The fragile peace between India and Pakistan who share half a century of antagonism including three wars, is daily shattered along the 485-mile-long line of control (LC) between them in the disputed northern state of Jammu and Kashmir.
Heavy-calibre machine guns routinely open up along the line that cuts across picturesque mountains, thick jungle and rivers for several hours. The slightest carelessness is certain death for the soldiers guarding it.
The firing, which started around a decade ago when Muslim militants began their war for an independent Islamic homeland in Kashmir, increased after India and Pakistan conducted nuclear tests in May - with Pakistan firing 268,700 rounds last month to India's 125,300.
The incessant chatter of machine guns is interspersed with deadlier fire from mortars, grenades, rockets and artillery shells as thousands of Indian and Pakistan soldiers, hunkered down in bunkers, man the world's "hottest" border between two nuclear-capable neighbours.
"India and Pakistan are neither at peace nor at war along the LC," said Col M.S. Kauchhur, the officer in charge of a large portion of the LC in the Rajouri sector, some 150 miles north of the state's winter capital, Jammu. Any mistake by either side can lead to fatal consequences, he said.
Damaged bunkers, some less than 50 metres apart hugging precipitous mountain slopes and others dotted along flat river beds across the zig-zagging line are repaired mostly under cover of darkness. Here stealth determines survival as Indian and Pakistani snipers lie in wait.
The LC came into being following the ceasefire between India and Pakistan after their first war over Jammu and Kashmir in 1948, a year after independence from British colonial rule. The line has remained relatively unchanged, except at a few places following two more wars, in 1965, - one more over Kashmir - and in 1971, which led to East Pakistan becoming Bangladesh.
Indian officers at Rajouri said Pakistani firing was a cover to infiltrate armed Islamic militants into the state to bolster Kashmir's nine-year-old civil war for an independent Muslim homeland, a war in which more than 20,000 people have died.
They said the militants, including Afghan, Sudanese and Pakistani mercenaries, were regularly pushed across the line at dusk, when firing normally intensified in order to given them the entire night to travel to insurgent bases inside Indian-held Kashmir.
"We are involved in a hazardous battle of wits along the LC, where one false step can be the last," said an officer from the Nangi Tekri post that overlooks Pakistan-held Kashmir at a height of around 5,500 feet and was captured by India during the 1971 war. "We operate like we would in a war zone," he said.
Pakistan denies this charge, saying it is merely retaliating against Indian "belligerence" on the LC.
Kashmiri militants and Pakistan are demanding a plebiscite for the state's self-determination, supervised by the UN. This was promised by India 50 years ago but has never held, with India claiming it has been overtaken by subsequent treaties.
Senior army officers said the LC was quiet after the 1971 war, with occasional flag meetings between picket commanders and exchanges of pleasantries and eatables by the soldiers on Hindu and Muslim religious festivals.
Army officers manning over 130 miles of the line in the "highly active" Rajouri area said that, since January, India and Pakistan had exchanged 1.53 million rounds of assorted fire or around 8,500 rounds daily. Both countries have also deployed additional troops along the line.