Anti-access/area denial

A2/AD strategy is a significant concern of US policy, viewing it as a weapon of weaker forces that could be used against the US military.[2] The US military considers that enemy adoption of anti-access/area denial strategies "may well be the most difficult operational challenge U.S. forces will face over the coming decades."[4]The Department of Defense developed the "joint air-sea battle concept for defeating adversaries across the range of military operations, including adversaries equipped with sophisticated anti-access and area denial capabilities".[7]

Chief of Naval Operations Adm. John Richardson has commented on the vagueness of the term A2/AD, saying: "To some, A2AD is a code-word, suggesting an impenetrable “keep-out zone” that forces can enter only at extreme peril to themselves. To others, A2AD refers to a family of technologies. To still others, a strategy. In sum, A2AD is a term bandied about freely, with no precise definition, that sends a variety of vague or conflicting signals, depending on the context in which it is either transmitted or received. [...] The Navy will avoid using the term A2AD as a stand-alone acronym that can mean many things to different people or almost anything to anyone."[8]

The KD-88 anti-ship missile is part of China's A2/AD weaponry.[9]

The concept of A2/AD has long been used by navies under names such as Command of the seas[6] and controlling the sea lines of communication. Naval A2/AD typically takes advantage of geographical features that limit access such as chokepoints or the water surrounding an island. A blockade is an example of a naval anti-access operation.[2]

Anti-ship missiles are a modern method of stopping a potential adversary from attacking by sea. China, Russia, North Korea, Syria and Iran all have developed or imported such weapons in an effort to develop a modern A2/AD strategy to counter United States' power projection from nearby waterways.[10] In response to China's pursuit of such A2/AD capabilities, the United States has developed the AirSea Battle doctrine. Other methods of area denial at a strategic level include aircraft carriers, submarines, surface-to-air missiles, ballistic missiles, cruise missiles, electronic warfare and interceptor aircraft.[11][12] Mines, coastal submarines, and attack craft could be employed in littoral areas.[3] Other area denial systems include cruise missiles, long-range strike aircraft, mines, and coastal defense artillery.[3] The term A2/AD was created in 2003 to describe the threats posed by long-range missile systems, precision munitions, and satellite technology that will make military operations in the littoral areas challenging for modern naval forces.[2]

The anti-access threat for the Army includes "theater ballistic missiles, cruise missiles, long-range rockets and artillery, weapons of mass destruction and other unconventional means, and information operations."[13] A2/AD strategies on land often take advantage of natural geographic features or bridges that can support anti-access operations.[2] Land-based area denial operations degrade the adversary's ability with techniques such as harassing fires, deception, and guerrilla-warfare-like tactics that avoid direct confrontation.[2] Land-based area denial techniques also include artillery, rocket, and missile strikes, mine fields, and chemical, biological, radiological, and nuclear agents.[3]

A no-fly zone is an A2/AD strategy in the air, prohibiting access to part of the airspace.[2] A2/AD can be supported by surface-to-air missiles such as the S-300 and S-400.[3] The threat on forward air bases from cruise and ballistic missiles can also impose anti-access.[3]

Attacks in cyberspace are an increasingly important part of the A2/AD threat.[2] Tactical cyber A2/AD operations block access to specific resources, while strategic A2/AD blocks access to cyberspace itself.[2]