The Emerging Anti-Access/Area-Denial Challenge

Emerging challenges to U.S. regional access and freedom of action have generated a great deal of conceptual debate over the past year. While access challenges transcend military threats, the Department of Defense (DoD) plays a unique role defending U.S. interests in the face of them. The defense-specific access debate gathered substantial momentum with the publication of DoD’s new strategic guidance and the Joint Operational Access Concept (JOAC) in January. In the new guidance, DoD argues for a sharp departure from the previous decade’s irregular wars, suggesting that the U.S. military prepare to deter and, if necessary, defeat more traditional adversaries and “project power despite anti-access/area denial challenges.” This all occurs in the context of twin strategic “pivots” toward Asia and Iran.

On Friday, May 18, CSIS will open a series of public discussions on anti-access/area denial (A2/AD) challenges, as part of the CSIS Military Strategy Forum sponsored by Rolls Royce North America. This first event will feature a keynote address by Lieutenant General George J. Flynn (USMC), the Joint Staff’s director of joint force development. It will focus on the JOAC and its impact on future joint military operations. DoD’s new strategic guidance mandated JOAC’s implementation as a key component in the U.S. military’s response to A2/AD. There are a number of key issues to consider on the subject as U.S. thinking evolves. Here are four critical questions and preliminary answers to them.

Q1: Why is A2/AD emerging now as a central theme in joint military operations?

A1: From the widest strategic perspective, U.S. access challenges manifest across traditional instruments of power. To the extent that these challenges adversely affect the security and prosperity of the United States and its allies, an open and stable international system, and/or freedom to transit the global commons, they will require coordinated U.S. government/allied responses to restore access. By definition, this will routinely involve military forces.

This is not meant to suggest that all access challenges are military in origin and character. In the Asia-Pacific region, for example, China is as much or more an active political and economic challenger—seeking to raise myriad barriers to U.S. influence—as it is a military competitor. Likewise, in the Middle East, Iran has some dangerous military capabilities but successfully avoids direct military confrontation with the United States, advances its interests, and limits U.S. freedom of action most often through cost-imposing political subterfuge. What is certain, however, is that when adversaries effectively combine political, economic, and informational tools with important military capabilities, the access challenge becomes more acute and potent.

U.S. military forces have a unique responsibility in helping secure access during times of peace, increased hostilities, and open conflict. The latter is the most demanding and, as of late, the subject of the greatest body of conceptual work. Under routine circumstances, maintenance of credible deterrent capabilities forward in key regions provides a stabilizing influence, actively underwrites the security of U.S./partner interests, and secures a concrete platform from which to expand presence and conduct operations in the event of heightened tensions or hostilities.

In the event of war or major violent conflict, U.S. forces will face a variety of A2/AD challenges that will originate both from the hostile designs of thinking adversaries and from the “unstructured” lethality of contagious instability. In virtually every instance, forward-stationed U.S. forces will be insufficient to overcome lethal or fundamentally disruptive A2/AD challenges and effectively resolve the crisis by themselves. Therefore, future combat operations—whether coercive air and sea campaigns or more wide-ranging joint interventions—will require the United States and its partners to project substantial military capability over considerable strategic and operational distances. A2/AD challenges frustrate our ability to do so.

Thus, at the “business end” of opposed operations, U.S. forces will increasingly compete with a diverse collection of adversaries for dominance across multiple domains—air, sea, land, space, and cyberspace. This will often occur without the benefit of extensive fixed U.S. regional basing and with “local” U.S. infrastructure under substantial pressure from hostile action. As a consequence, the character of specific lethal access challenges, their diversity, and their sophistication will differ significantly. In combination, the real constraints of finite military capability, the increasing lethality of virtually every conceivable contingency environment from peace operations to regional war, and lower U.S. risk tolerance make deep thought about lethal or fundamentally disruptive A2/AD challenges an urgent strategic priority.

Q2: What are anti-access challenges?

A2: While most often presented in combination, anti-access (A2) and area denial (AD) challenges are important to consider separately as well. To U.S. strategists, A2 challenges are intended to exclude our forces from a foreign theater or deny effective use and transit of the global commons. More broadly, A2 challenges might first involve political and economic exclusion, where competitor states actively attempt to deny the United States the broad political and economic influence it has long enjoyed. In military terms, this may translate into blanket denial of basing, staging, transit, or over-flight rights.

Under more hostile circumstances, lethal A2 instruments include sophisticated longer-range adversary capabilities and methods like ballistic missiles, submarines, weapons of mass destruction, and offensive space and cyberspace assets. Equally dangerous but less technical A2 methods might include terrorism or proxy warfare employed by U.S. opponents to open alternative “fronts,” distract attention, and impose excessive costs politically.

Hostile A2 capabilities and methods are intended first to see U.S. risk calculations breach “high” or “unacceptable” levels during planning in order to prevent U.S. regional intervention altogether. But, in the event of active hostilities, adversaries would employ their lethal A2 assets from a distance to keep the United States at arm’s length, perhaps deny introduction of U.S. forces and capabilities in substantial numbers, and barring either outcome, exact prohibitively high costs on the United States when and if U.S. forces attempt to breach an opponent’s A2 defenses. Given China’s increased assertiveness, current military capability, and raw potential, an acute, sophisticated, and comprehensive A2 challenge is emerging in Asia. There is clearly some grand strategic risk associated with excessively militarizing the nature of the competition between the United States and China, as the locus of real competition may lie substantially outside the reach of DoD and the military instrument.

Q3: What are area denial challenges?

A3: Over the near to mid-term, lethal area denial (AD) challenges present U.S. strategists with the most prolific barriers to effective theater entry and operation. Every conceivable contingency employment of air, sea, or ground forces will need to overcome significant AD obstacles. Lethal AD threats manifest at close range. Their effects begin accruing as U.S. forces enter a hostile or uncertain theater to conduct joint operations, and in the end, they complicate our attempts to establish an effective presence in, over, or in range of an adversary’s territory or interests. Lethal or disruptive AD challenges are present and can attack U.S. vulnerabilities in all five key domains—air, sea, land, space, and cyberspace.

They do so first by providing the means to physically resist U.S. entry into theater. Subsequently, they limit freedom of action once U.S. forces have arrived. Then, they frustrate our efforts to rapidly achieve favorable strategic and operational outcomes. And, finally, they threaten to impose very high costs on U.S. forces should extended military operations become unavoidable. Like A2 challenges, AD threats can poison U.S. risk calculations well before the initiation of an operation by increasing the mission’s perceived degree of difficulty. After entry, AD challenges force U.S. decisionmakers to persistently question the mounting costs associated with continued operations.

Lethal AD capabilities range from the sophisticated to the crude but effective. They include cruise and ballistic missiles; weapons of mass destruction; mines; guided rockets, mortars, and artillery; electronic warfare; and short-range/man-portable air defense and anti-armor systems. Revolutions in information; personal computing, communications, and networking; and irregular and hybrid forms of warfare—combined with the proliferation of precision weapons and improvised battlefield lethality—substantially widen the universe of effective AD adversaries from individuals and loosely organized groups to sophisticated regional powers. Likewise, the networked mobilization of foreign popular, nonviolent resistance may also prove to be a significant challenge to freedom of action in the future as well. To the extent U.S. opponents can leverage all of these capabilities and methods both directly and through proxies, the more the AD challenge will expand geometrically. As noted above, an effective combination of political, economic, and informational methods with sophisticated lethal and/or disruptive AD capabilities will make any specific challenge more resilient and potent.

Whereas lethal A2 challenges are virtually always the product of deliberate enemy design, AD challenges don’t have to be. They can be “structured” or “unstructured.” Iran’s hybrid “mosaic defense,” for example, is structured. Though highly unconventional, it is part of a coherent cost-imposing strategy. Its combination of ballistic and cruise missiles, unconventional naval forces, and hybrid ground defenses—matched with tight Persian Gulf geography, Iran’s physical depth, and its deep ties to regional proxies—offer a complex structured AD challenge that strategic and operational planners would have to account for in the event of hostilities.

U.S. forces are likely to face unstructured AD challenges in the course of interventions conducted under conditions of widespread disorder, where local authorities have little or no control over outcomes. Imagine military operations conducted in the same Iran described above; this time, however, after failure of the regime and in the midst of an ongoing civil war. U.S. forces might face multiple competing adversaries all boasting some relatively sophisticated, disruptive, and lethal AD capability but employing it all haphazardly under no discernible centralized command and control, making comprehensive defeat more problematic.

Q4: What will the CSIS event series add to the A2/AD conversation?

A4: Through the CSIS “access” series, we hope to break down the A2/AD challenge from the various angles described above. This ranges from the grand political and economic to the highly disruptive and lethal. We want to hear from senior leaders and experts both on the “access” problem itself and on the alternative concepts proposed for overcoming it in its various forms. Finally, we want to consider what might be missing from collective thinking about A2/AD. One critical gap, for example, may be meaningful consideration of A2/AD challenges that emerge largely from outside the realm of military competition and violence; political and economic exclusion, for example, underwritten by the strategic use of information and the nimble employment of disruptive cyber warfare. This kind of strategic combination of nonviolent political, economic, and informational instruments targeted specifically at U.S. vulnerabilities may have adverse “warlike” effects on core U.S. interests, all while precluding the use of military power as a legitimate response.

Nathan Freier is a senior fellow in the International Security Program at the Center for Strategic and International Studies in Washington, D.C., and a visiting research professor at the U.S. Army War College’s Peacekeeping and Stability Operations Institute in Carlisle, Pennsylvania.

Critical Questions is produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).

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Nathan Freier