A tweet posted last week by Peter Singer, a co-author of the book Ghost Fleet and a strategist at the New America Foundation, shows his book couched up against what appears to be a Battelle DroneDefender anti-drone rifle in a tent at Fire Base Bell outside Makhmour, Iraq.

The Things They Carried Into War:

Scene from Fire Base Bell in Iraq.



HT @kudzu81 and stay safe#ghostfleet pic.twitter.com/dfPzAslP2y — Peter W. Singer (@peterwsinger) July 22, 2016

The advent and proliferation of small, cheap drones has had a lasting effect on the battlefields of the 21st century. From Syria to Ukraine, the devices have been used in myriad ways, from filming propaganda videos to observing enemy locations. The presence of a U.S. anti-drone system, while a seemingly sensible counter-measure against the Islamic State's fondness for using the remote-controlled aircraft, is a small glimpse into how the American military is adapting to evolving battlefield threats in the wake of its two protracted ground wars in Iraq and Afghanistan.

It is unclear when the picture was taken, though the small American base was first stood up in March. Now renamed the Kara Soar Counter-Fire Complex, the outpost has been responsible for providing artillery support for Iraqi and Kurdish peshmerga forces as they attempt to move northwest into the Tigris River valley.

According to the rifle's description on the manufacturer's website, the rifle takes "no extensive training" and "disrupts the adversary's control of the drone, neutralizing it so no remote action, including detonation, can occur." The rifle is a "non-kinetic" weapon, meaning it doesn't use bullets.

The system has the ability to disrupt the user's control link to their drone as well as its ability to sync with a GPS network. It is unclear what type of frequency the rifle uses to attack its target, but the size of the dual front-mounted antennas suggest that the disruption pulse is distributed across multiple radio frequency bands. The rifle has a range of roughly 400 yards, will hit a drone in a 30-degree cone and can be ready to use and fire in less than a second, according to the site. Aside from the antennas and the attached battery pack, the anti-drone rifle appears to be very similar to the M-16/M-4 series of rifles carried by U.S. troops, including a similar stock and attachment system for accessories such as scopes and flashlights.

While small drones can be used to observe enemy locations, they can also be used to coordinate indirect-fire weapons such as mortars, rockets and artillery. Indirect-fire weapons are often fired beyond the line of sight of their intended target, making the presence of an observer that can see where the rounds are impacting invaluable. Using drones to observe and coordinate artillery and mortar strikes has been nearly perfected in eastern Ukraine, where Russian-backed separatists have used the tactic almost daily since the war started there in 2014.

In March, an Islamic State rocket attack killed Marine Staff Sgt. Louis Cardin and wounded eight others at Fire Base Bell. Pentagon officials at the time said that the Islamic State had used 107mm Katyusha rockets. First debuting on World War II's eastern front, the Katyusha rocket has been a staple in conflict zones ever since, and has been used extensively in Iraq and Afghanistan.

The commander of the Marine unit stationed at Fire Base Bell recently told reporters that the base came under numerous rocket attacks during the unit's 60-day stay there. It is unclear if the Islamic State used a drone to make their strikes more accurate, but its likely that the terror group used the small devices to at least perform some type of reconnaissance prior to targeting the American contingent.