In this particular passage in the story, a stray dog has wandered over to the Indian side of the border in search of companionship. The Indian soldiers he encounters are at first quite friendly towards him; one throws him a couple of biscuits. They jokingly wonder aloud whether the dog is Indian, in which case he's okay, or Pakistani, which means he should be blown away.

But in the midst of the general air of jocularity there are disturbing hints as to what is to come. One of the soldiers digs the heel of his boot into the ground and says "Dogs, too, better now make up their minds as to whether they’re Indian or Pakistani". This is an important moment in the story because the soldier is digging his heel in, both literally and metaphorically. He's showing the intransigence of both sides in this bitter dispute between the two neighboring states.

For now, it's all smiles. But later on things will turn uglier—the dog ends up being terrorized and killed. It would seem that even a dog, a poor, humble creature who just wants companionship, has to take sides since both Indians and Pakistanis dig their heels in for the long and bitter conflict ahead.