Here's just how close a sniper can get without you ever realizing they were there

US Army

A southern black racer snake slithers across the barrel of junior U.S. Army National Guard sniper Pfc. William Snyder's rifle as he practices woodland stalking in a camouflaged ghillie suit during a 1-173 Infantry training exercise, April 7, 2018, at Eglin Air Force Base.

• US military snipers train to be able to hide from enemies at distant observation posts, as well as patrols in the field.
• Even during stalking training, where snipers are focused on observers at their target, "the goal is that they have 360-degree concealment," a US Army sniper instructor told Insider, adding that "if there were patrols in the area that you could be in that position and ... the casual observer is not going to notice you."
• There is no specific distance that snipers train to be from a casual observer and remain hidden, but Insider previously witnessed a Marine Corps scout sniper evade detection from a group standing about three feet away.
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Snipers train to put fire on a target without giving away their position, and that requires staying hidden from threats as close as patrols in the field as as distant as observation posts.

Stalking training, a type of exercise in which snipers stealthily approach a target, set up a forward firing position and put two shots on the target without exposing themselves, is one way snipers master concealment techniques.

Trained observers at the target hunt for them. And, to make it more of a challenge for the snipers, instructors follow them around as they move along the stalking lanes, letting the observers know the general direction to look in.

U.S. Army Reserve photo by Capt. David Gasperson

A U.S. Army sniper and infantryman with the U.S. Army Sniper School poses during a video shoot at Fort Benning, Georgia, Dec. 13, 2018.

"Instructors are within 10 feet of them," Army Staff Sgt. Joshua Jones, an instructor at Fort Benning, told Insider. "Even though the target truck is farther away, it tells the [observers] that within 10 feet of wherever that person is, there's a sniper."

While their focus is on the observers at the target, snipers are expected to maintain effective all-around cover and concealment in the field. "The goal is that they have 360-degree concealment," Jones said.

There is no specific distance, the veteran sharpshooter said, that snipers train to be from a casual observer and remain hidden, but it is something they are expected to think about.

"The concept behind that is basically if there were patrols in the area that you could be in that position and ... the casual observer is not going to notice you," he further explained, telling Insider that trained snipers "should be able to withstand that kind of observation without anybody busting" their position.

The instructors in the field, known as "walkers," will take points off a trainee's grade for improper movements or vegetation that might expose them from a different angle, if not from the target.

When Insider observed Marine Corps scout sniper training last September, one of the instructors set up a forward firing position as a demonstration. This Insider reporter and around a dozen Marines were directed into the field by other instructors. Once out there, the group was informed that a sniper was in position about three feet away.

No one spotted him, at least not immediately, and we were looking for him.

Ryan Pickrell/Business Insider

A seasoned Marine Corps sniper hiding in the field at Marine Corps Base Quantico in VA

Snipers use a mixture of natural and artificial materials, such as jute and various vegetation, to customize their ghillie suits and build screens, tools that help snipers to achieve concealment and camouflage and avoid enemy detection.

Concealing oneself from an lookouts and surveillance is about putting "anything you can between you and whatever might be observing you," another Fort Benning sniper school instructor previously told Insider. The idea is to break up the human shape and blend into the negative space the eye overlooks.

"Don't be the bush," Insider once heard a Marine Corps scout sniper say. "Be the space between the bushes."

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