In the popular imagination, the Indo-Pakistan border is a long, sturdy, electrified and carefully monitored fence along which Indian soldiers are constantly patrolling. People tend to think of rows of barbed wire in deserted land that would be impossible to cross over, which is why it seems so unusual when we hear about infiltrators managing to make their way over into India, as authorities say happened in the ongoing Pathankot attack.

The reality of course is much more complicated. The international border is thousands of kilometres long and traverses deserts, rivers, urban areas and wilderness.

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The video above gives you a sense of what the border actually looks like, albeit at a time when the area was flooding. The fences from the popular imagination are still there, but it's not exactly territory that allows for easy monitoring or patrolling. In fact, the border to Punjab's Gurdaspur district – where terrorists reportedly crossed over to carry out the ongoing Pathankot operation as well as last year's Dinanagar police station attack – features a particularly challenging stretch because the Ravi river passes through it. The border straddles an entire network of streams and tributaries, leaving lots of potential weak points that infiltrators could take advantage of.

A small cross section of the border, like the one below, gives you a sense of how difficult it is to monitor a fence that is also crisscrossed by an unpredictable body of water.

To make things worse, the water is also sometimes deliberately deflect by Pakistan, leading to flooding in certain areas that has affected Border Security Forces camps in the past.

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