The Importance of Area Denial in War

The military concept of delaying or preventing opposing forces from capturing a specific area is as old as warfare. History is littered with brave examples of the few holding off the many, though "famous last stands" are just as numerous. When discussing contemporary anti-access and area denial, however, the focus is typically on naval and aerial operations that establish tactical superiority, not ground operations. Large naval vessels and fighter aircraft often benefit from incredible technological advancements at considerable expense, enhancing their impact on the battlespace. Ground forces tend to have more numerous, lower-cost platforms and are often overlooked. Yet area denial efforts on the ground have an incredible effect on the conduct of modern warfare, especially in recent hybrid conflicts.

Rather than establishing complete physical control over a particular position, the concept of anti-access and area denial (known in military circles as A2/AD) focuses on making a location off-limits to the enemy, thereby forcing enemy fighters into terrain of the defenders' choosing. Those defenders can then concentrate and allocate forces efficiently to their advantage, gaining superiority (if only temporarily). This can often be achieved with little cost in terms of time, equipment and men. Anti-access and area denial is a critical strategy often used by weaker forces against stronger ones, because preventing the enemy from taking and holding a particular area is often easier than controlling it.

There are two elements of area denial operations in ground warfare. The first is actual maneuvers that delay or prevent the movement of opposing forces. This can be achieved with countermobility operations such as deploying barbed wire across front lines or laying dense minefields that can cause significant attrition, thereby forcing opposing troops to advance slowly as they sweep and clear the area. The second element is the use of less manpower-intensive standoff weapons: long-range artillery systems that can devastate military formations through either immense saturating fire or precise deployment of large warheads, making military operations within their reach extremely difficult or even impossible. During the Cold War, Soviet doctrine also called for use of nerve agents for area denial. Nuclear and chemical weapons have often been considered because of their ability to affect larger areas.

To be effective, area denial efforts do not necessarily need to halt or drive out opposing forces entirely. By inflicting intolerable losses or by funneling opposing forces to selected areas, defensive ground forces can be more efficiently deployed along the gaps in these areas, preventing the most favorable avenues of approach and raising the cost for enemy fighters to traverse them. Area denial can also be an effective way to disrupt the establishment of capable logistics nodes that support further advances by combat elements.

Present-Day Examples

We need look no further than recent and ongoing conflicts to explore the usefulness of dedicated anti-access campaigns. In eastern Ukraine, the extensive use of BM-21 Grad multiple launch rocket systems in the area near the Russian border made it impossible for Ukrainian security forces to operate there. The massive personnel and equipment losses they suffered not only damaged their ability to patrol near the border and sustain military operations, but also provided pro-Russia separatists with relatively safe staging areas from which to mount counteroffensives. Even battles over particular locations, such as Donetsk airport, devolved into mutual attempts to deny control of the facility by simply firing artillery into it until barely any defendable positions remained.

Conversely, area denial attempts in Yemen are not conducted by massive weight of fire, but through the use of accurate guided weapons with large warheads. Over the past weeks, a number of Tochka guided missiles were launched by forces loyal to former Yemeni President Abdullah Saleh at forward operating bases used by Saudi-led coalition forces. These strikes caused significant casualties, potentially weakening the resolve of Saudi coalition partners to remain committed to the fight. At the same time, these strikes are also destroying valuable equipment as well as disrupting the coalition's attempts to set up command centers and logistics depots near the front lines.

In the fight against the Islamic State in Iraq, U.S. forces have consistently applied the same anti-access concept, denying the use of ridgelines and hilltops to Islamic State fighters. Likewise, the militant group is itself adept at using improvised explosive devices and a handful of mobile sharpshooters to hamper Iraqi forces from taking ground from them, especially in urban areas.

Countering Area Denial

It is important to remember, however, that area denial is not a one-sided ploy — attacking forces have their own doctrinal approach to overcoming an enemy's efforts to prevent access. In Yemen, Saudi forces deployed Patriot missile defense systems to interdict incoming projectiles, though these have not been able to effectively prevent all the Tochka strikes. In Ukraine, counter-battery radars have become one of the most important tools of the Ukrainian military when it comes to protecting its forces from separatist and Russian artillery. The ability to accurately pinpoint where artillery rounds are coming from enables counter-battery fire, meaning that the enemy cannot use indirect fire with impunity. But these technological countermeasures are only part of the solution. The other aspect is a change in tactics: modifying the pattern of deployments and rethinking attainable objectives while confronting area denial operations. Changes in behavior, techniques and procedures play an important part in improving the survivability of forces in combat but can be a double-edged sword. Dispersing forces across a given area can prevent susceptibility to massed artillery stirkes, but such a move can erode the concentrated combat effectiveness of an attacking force, while benefitting the defenders.

Of course, aerial operations and naval access can and do play an important part in area denial for ground forces. In Ukraine, area denial efforts would not have been as successful or sustainable had the Ukrainian air force had free rein to strike separatist positions. Denying air space to Ukrainian combat helicopters and ground attack aircraft was an important first step to holding up the advance of ground forces.

Similarly, in Yemen, the guided missile systems that Saleh loyalists are now applying against the advancing coalition ground forces have been a priority target of the Saudi-led air campaign. The lengths to which Saleh's forces go to protect these weapon systems and hide them from coalition airstrikes shows how important they are to the anti-coalition strategy. It also highlights the need for accurate and timely intelligence regarding area denial and counter-area denial operations. To maintain such capability, strict operational security is required. For forces defending against area denial efforts, intelligence, surveillance and reconnaissance assets become critical — including foot patrols, spies, radio interception stations, satellites and drones, among other intelligence collection sources.

Along with improving technological countermeasures and more effective procedures to increase resilience against area denial weapons, expanding intelligence capabilities is key to identifying, locating and defeating such efforts in ongoing wars and the inevitable wars to come.