An ISIS militant teaching a class on how to behead captured prisoners was nailed in the head by a British sniper attached to the elite Special Air Service from 1,000 meters away.

The International Business Times says the 20-person execution class scrambled as the instructor's head was taken "clean off" by the round from an Israeli-made .338 caliber DAN rifle. The bullet is designed to "tumble" as it moves through a target's body, inflicting massive damage.

Israel Weapon Industries DAN .338 Bolt Action Rifle

"One minute he was standing there and the next his head had exploded," a British military source told Express UK. "The commander remained standing upright for a couple of seconds before collapsing and that's when panic set in. We later heard most of the recruits deserted. We got rid of 21 terrorists with one bullet."

Express also reported that British SAS units are deployed in small numbers to combat Daesh terrorists to avoid an all-out ground war. The militants will either swarm to a location, making an airstrike a better defense or retreat using tunnels.

One tactic the SAS uses is setting "desert death traps" for jihadis by laying out dummies dressed as officers. The terrorist fighters are alerted by scouts and locals, take the bait, and are then gunned down by SAS snipers.