sniper; sharpshooter
A military marksman who shoots from a concealed position. The term is neutral and commonly used in news and military contexts.
A sniper was hiding on the rooftop of the building.
He was trained as a sniper in the army.
Compound of 狙撃 (sogeki, 'sniping') and 兵 (hei, 'soldier'). The word is a straightforward Sino-Japanese formation.