What risk does the sniper take in "The Sniper"?

In Liam O'Flaherty's short story “The Sniper,” the title character takes a risk as he waits on a rooftop, watching for a target. He wants a cigarette, but he knows that even such a small light can draw unwanted attention. He decides to take the risk anyway. At once, a bullet flies past his head, then another. The enemy has noticed his position, and the sniper quickly rolls over behind a chimney. He cannot see the enemy sniper.

As the story continues, the sniper takes another risk. Knowing that the enemy sniper is watching his position, he decides to open fire on the car and informant below. He kills a man in the car and the woman informant but is hit by a bullet from the other sniper, who again has discovered his position.

The sniper is now determined to take out his enemy counterpart, and yet again he takes a risk. He reveals his position by pushing his rifle up over the edge of the roof. The other sniper fires immediately. The sniper then allows the rifle to fall to the street below and hangs his left hand over the roof, pretending to be dead. The enemy sniper, thinking he has done his job, shows himself, and the sniper fires his revolver. His enemy drops. This time the risk pays off. He has won, but his sense of victory quickly diminishes when he descends to the street, turns over the body, and realizes that the enemy sniper is his own brother.

What risk does the sniper decide to take?

Although the Republican sniper knows it is a risk because the flash of his match might be seen in the darkness, he decides to have a cigarette anyway. It is a poor decision. He is young, and perhaps this is why he makes the error in judgment. Though he lights the cigarette as quickly as he can and blows out the flame, the sniper on the rooftop opposite his own sees the flash and quickly fires at him. He takes one more drag on his cigarette and then puts it out. He crawls away to the left because he has given away his exact position to his enemy. When next he peeks over the edge of the rooftop, another bullet whizzes over his head.

What specific threats does the sniper face in "The Sniper"?

It is clear that the major threat to the Sniper's life in this short story as we are presented with it is the threat of the other unknown sniper who is on the roof opposite where he is based. Note how the Sniper discovers the existence of his enemy. The Sniper shoots the informer and the solder in the tank and then suddenly, he is shot at himself:

Suddenly from the opposite roof a shot rang out and the sniper dropped his rifle with a curse.

The Sniper has just revealed his position to his enemy who has now shot him and successfully managed to wound him. Of course, the rest of the story tells us how this external conflict is resolved as these two snipers duel in a battle of wits for their lives.