ch-46 helicopter

The view from our “room” in Musa Qala, Afghanistan.

History is full of examples of successful military surprises.  Examples of effective early warning strategies are more difficult to find, but they range from the simple to the sublime. Animals such as dogs, horses, and even guinea hens have been used to warn of the enemy’s approach. According to the ancient historian Livy, the Romans used geese to detect a night attack on Rome by the Gauls in the 4th century. Trip wires and noise makers are another classic example of long-used early warning devices. Don’t forget scouts and observation and listening posts. As early as the Vietnam war, radio and electronic detectors have also been used to alert the presence and movement of men and material.

     High ground has always been considered important for observation, usually supplemented by watchtowers, like those positioned along Hadrian’s Wall in Britain and the Great Wall of China. Aviation took high ground to another level. In May 1863, an observation balloon of the Army of the Potomac detected General Lee’s Army of Northern Virginia moving across the Rappahannock to engage in the Gettysburg Campaign.

Not only enemy movements but civilian trends also contribute to the overall preparation of the battlefield, understanding routes of approach and departures, as well as choke points and meeting places.  However, these observations are best collated and quantified when the object of surveillance is unaware of the monitoring.

USMC Early Warning Capabilities

Remote sensor capabilities first came into play in September 1966 when Secretary of Defense Robert McNamara established the Defense Communication Planning Group (DCPG). The DCPG was tasked with developing a system to monitor the movement of supplies and men from North Vietnam to South Vietnam via the Ho Chi Min Trail. Under their auspices, the Navy was tasked to develop an RSS (Remote Sensor System) for deployment in Vietnam later that year.

The first operational sensors were deployed thirteen months later. Intelligence collected from the sensors was utilized by the Air Force to direct strike aircraft onto enemy targets. In response to the mounting pressure on the Marines fighting at Khe Sahn, elements of the RSS were redirected to support them.

Seismic and acoustic sensors were air delivered and emplaced by ground reconnaissance elements around the 26th Marine Regiment’s defensive perimeter, focusing on possible ingress/egress routes. As the North Vietnamese began to attack, the sensors provided a limited role for intelligence collections on enemy artillery and mortar positions, but their value regarding enemy movement became an essential contribution to the US Marine’s victory.

What is USMC Ground Sensor Platoon today?

ground sensor platoon

2nd GSP platoon pic, a week before we deployed to Iraq.

Fifty years later and Ground Sensor Platoon has morphed into a small specialized unit that seeks out and monitors insurgency and high-value targets for offensive operations. They also prevent larger-scale infantry units from ambush, improvised explosive devices, or other types of attacks. GSP is classified as an intelligence unit but holds firm to our infantry background.

A GSP team consists of four Marines, three 0311s (Infantry), and one 0621 (Radio Operator). Teams are usually led by a Corporal (E-4) or Sergeant (E-5). On deployment, our teams are individually attached to an assigned infantry battalion in an AO (Area of Operations), and although the role of sensors is primarily surveillance, target indication, and early warning, they can and have been utilized in many more roles such as force protection, sniper support and target visual identification (VID).

8621 Training

To obtain my secondary Ground Sensor MOS and security clearance, I was given orders to attend an eight-week Sensor Surveillance Operators Course (SSOC) at the Navy/Marine Corps Intelligence Training Center (NMCITC) in Dam Neck, VA. I learned basic intelligence, mapping, equipment, planning, monitoring, reporting, and emplacement techniques during the course. The training gave me the ground-level skills needed to deploy ground sensors in combat operations.

Diversionary Tactics

Afghanistan terrain

Picture by Thumper of the terrain surrounding Now Zad.

I’ve employed ground sensors in several countries for various missions. Each country had its own set of challenges. In Afghanistan, the terrain was medieval. I vividly remember using my E-Tool for the first time and feeling like I was mining for precious metals. It was loud, and it was hard. It was volcanic rock, devils ground.

There was the terrain and the local population, but they rarely ventured much beyond their village or town. Because of this, they knew every blade of grass, every rock formation, and every disturbance to the land. We had to use diversionary tactics to insert our team, usually in the dead of night.

An example of this is a mission we conducted with Sniper Team 4, “Erebus 4”. Our mission was to deploy a Scorpion sensor equipped with a day and IR camera. The S-2 OIC had tasked SET D with providing surveillance on a village to the east of the Musa Qala District Center. Snipers would provide overwatch.

At 0200, we set off from the District Center in a five-vehicle (MATV) mounted patrol. The patrol advanced to a position west of and overlooking the village situated in a wadi. It was about a good 50-foot drop to the bottom of the valley floor if you lost your footing. The patrol came to halt on a strip of the road out of view of the village below. EOD was in the lead vehicle, and they pushed forward 200 meters while the remaining vehicles stayed static. Ten minutes later, a massive explosion broke the silence of the night. That was our cue. EOD had set off a controlled detonation up ahead. We dropped off the vehicles and crept towards the ridgeline establishing a 360 defensive position. There were six of us, four snipers and two sensor operators. The remaining vehicles took off like a bat out of hell, providing a mini sandstorm that aided in covering our team’s movement. Diversion executed.

As the sounds of the escort patrol disappeared, I started to see lights flashing on and off on the opposite ridgeline. First, it was a flash off to the right, then two flashes off to the left. It looked like the Taliban was directly in front of our insert position. I thought to myself, “Fuck, they saw us.” We observed for a couple of hours, and the lights finally dimmed.

Tools of the Trade


ground sensor platoon

One of the few times I marched the platoon during training in Quantico, VA.

I was trained on the Tactical Remote Sensor Systems (TRSS) sensor system in Dam Neck. TRSS systems consist of seismic, acoustic, magnetic, infrared sensors, and surveillance cameras. TRSS was capable of detecting the presence and movement of personnel and vehicles and could provide near real-time monitoring of sensor activity within the line of sight of a radio repeater or the TOC (Tactical Operations Center).  Another significant feature this system brings to the table is extended range detection and surveillance capability without having to maintain a physical presence in the immediate target area.

The downside to TRSS was that the sensors emplaced in the field had to maintain a line of sight with a radio repeater or the TOC (Tactical Operations Center). If I didn’t have a line of sight, the sensors would not report. It was a big pain in the ass, especially in mountainous terrain. The other key limitation was the battery life of the sensors and the fact that there was no alternative power source such as a solar or rechargeable battery or a tactical extension cord.   

SatCom (Satellite Communications) Systems

During my pre-deployment training for Iraq, I was also introduced to SatCom Systems. The differences between the two systems were huge. SatCom sensors provided day and night imaging and an advanced acoustic sensor with a more sophisticated target classification capability and target location. The SatCom sensors I operated had a much longer battery life than TRSS sensors, especially for the systems with an external battery pack with six 5590 batteries. It could stay in the field much longer.

SatCom systems were also great because I could program the system in the field and only have to worry about line of sight with the satellites in the sky. Much less challenging, line of sight-wise. Deploying one of these could be done relatively quickly…unless you ran into Murphy and his bullshit law. Plug batteries into System, Load your program, Site the cameras in, and ensure you have good images, camouflage, police area, and exfil. It was as easy or hard as that, depending on Murphy.

The downside to SatCom systems was the size of the system and cameras (Day/IR). We had to learn how to camouflage our systems to blend in with the local topography.  Adding insult to injury, we were issued fake silicon rocks to use as camouflage for the bulky systems. The fake rocks were a joke, and we took them to the side in favor of our homemade solutions. We used spray foam to build a “honeycomb” over the lens of the camera, leaving just enough of a hole for us to receive good, clear images.

Hiding Gear in the Suck

marine corps surveillance camera

SatCom camera camouflaged with spray foam. We deployed this system in Salaam Bazaar.

One of the many problems I ran into in the Middle East is that the people lived in one place and didn’t move around much. They weren’t taking the family on a trip to another city for Ramadan. That just wasn’t happening, it was too dangerous for that shit. The problem is that the people knew the land like the back of their hands. It’s challenging to hide a bulky ground sensor in the ground without someone noticing it. We were doing the same thing as the insurgents who set IEDs, except we didn’t know the ground like the enemy.

In Afghanistan, we deployed a string of ETU II (Encoder Transmitter Unit) sensors that were compromised by the Taliban and booby-trapped with six pressure plate IEDs. That could have been game over. It was the Taliban “Counter Sensor Teams,” the bastards. We knew we were being watched everywhere we went. It was a deadly game of cat and mouse.

I cherish my years in GSP, even though I bitched and moaned through most of it. I faced a lot of fears. I’ve been on teams that meshed really well, understood each other’s role in the team, and operated as one cohesive unit. I’ve also been on teams that were like a toxic relationship. That’s just the way it was. I miss the guys most of all. They are brothers. But sometimes, it brings back memories of hard times. I’m grateful to have had the opportunity to serve with them. I’ll be posting stories of individual missions we conducted in later posts. Cheers.



Bradley C. Palm, and Ryan P. Richter. “Mobile Situational Awareness Tool: Unattended Ground Sensor-Based Remote Surveillance System.” PhD diss., Naval Postgraduate School, September 2014.

U.S. Marine Corps: Department of the Navy. “Remote Sensor Operations.” MCRP 2-10A.5, April 4 2018.

Department of the Navy: HQ USMC. “Ground Sensor Surveillance T&R Manual.” NAVMC 3500.17A, September 2010.


OldSarg · July 21, 2018 at 01:04

Great post! Best yet.

Anna · July 23, 2018 at 21:14

Powerful words!

Thomas Hill · May 29, 2019 at 09:19

I am a old school SCAMP unit member from 1975-76. Thanks for letting us old timers what the USMC is doing with the Sensor field. My 8621 mos training was OJT in Okinawa (1st class to do OJT training)

Rolland Frum · November 22, 2019 at 11:25

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Bill Lavelle · December 27, 2020 at 18:13

Hello Mike,
I’m a USMC Vietnam Veteran. I was originally assigned to the 3rd MarDiv Ground Surveillance Unit in the Northern I Corps in July of 1969. When the 3rd MarDiv pulled out of Vietnam, I moved down to the 1st MarDiv G2 SCAMP Team near DaNang in Jan 1970 and eventually rotated back to the States in July 1970. I was a Sensor Implant Team leader and participated in 30+ Implant missions among other duties. There are about a dozen of us Vietnam “SCAMPERS” still alive and meeting yearly to reminisce about our history together. If you any interest in talking to me or any of my Vietnam Marine Brothers, just let me. . (We have lots of stories to tell)
Semper Fi 🇺🇸
Bill Lavelle
570 468-9813

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