Grey-zone (international relations)

The grey-zone (also grey zone, gray zone, and gray-zone) describes the space in between peace and war in which state and non-state actors engage in competition.

Use of the term grey-zone is widespread in national security circles, but there is no universal agreement on the definition of grey-zone, or even whether it is a useful term, with views about the term ranging from "faddish" or "vague", to "useful" or "brilliant".^[1]

The grey-zone is defined as "competitive interactions among and within state and non-state actors that fall between the traditional war and peace duality." by the United States Special Operations Command.^[2] A key element of operations within the grey-zone is that they remain below the threshold of an attack which could have a legitimate conventional military response (jus ad bellum).^[3][4] One paper defined it as "coercive statecraft actions short of war", and a "mainly non-military domain of human activity in which states use national resources to deliberately coerce other states".^[1] The Center for Strategic and International Studies defines the grey-zone as "the contested arena somewhere between routine statecraft and open warfare."^[5] British Defence Secretary Ben Wallace called the grey-zone "that limbo land between peace and war."^[6]

Grey zone warfare generally means a middle, unclear space that exists between direct conflict and peace in international relations.

According to Vincent Cable, examples of grey-zone activities include undermining industrial value chains or oil and gas supplies, money laundering, and the use of espionage and sabotage.^[7] According to Lee Hsi-ming "gray zone conflict is characterized by using the threat of force to create fear and intimidation."^[8] US Navy admiral Samuel Paparo has termed gray zone activities "illegal, coercive, aggressive and deceptive" (ICAP) following the preferred term of Romeo Brawner Jr.^[9]

The term grey-zone was coined by the United States Special Operations Command^[10][11] and published in a 2015 white paper.^[12] The concept of the grey-zone is built on existing military strategies; however, information technology has created radical new spaces which have expanded what is possible. Modern hybrid warfare and political warfare operations primarily occur in the grey-zone.^[13]

In the late 2010s, China escalated to grey-zone warfare with Taiwan in an attempt to force unification with the smaller country.^[14] Taiwan's Coast Guard Administration has had to expand rapidly to meet the rising grey-zone challenge.^[15] China's grey-zone operations against Taiwan in the maritime domain are meant to establish presence while maintaining plausible deniability.^[16]

It is generally believed that non-democratic states can operate more effectively in the grey-zone as they are much less limited by domestic law and regulation. It can also be very hard for democratic states to respond to grey-zone threats because their legal and military systems are geared towards seeing conflicts through the sense of war and peace with little preparation or consideration for anything in between. This can lead democratic states to either dramatically overreact or under-react when faced with a grey-zone challenge.^[17]

The concept of grey-zone conflicts or warfare is distinct from the concept of hybrid warfare,^[18] although the two are intimately linked as in the modern era states most often apply unconventional tools and hybrid techniques in the grey-zone.^[19] However many of the unconventional tools used by states in the grey-zone such as propaganda campaigns, economic pressure and the use of non-state entities do not cross over the threshold into formalized state-level aggression.^[17]

China has undertaken a grey-zone campaign in the South China Sea, adopting a “salami-slicing” philosophy, whereby they pursue consistent incremental gains which when viewed in isolation are too inconsequential to amount to large scale retaliatory measures, however when viewed in totality can amount to significant changes in the region.^[20]

The South China Sea is a highly contested region, with China, Taiwan, the Philippines, Malaysia, Brunei, and Vietnam all staking overlapping claims to the region. China has claimed that it has jurisdiction over the near entirety of the South China Sea, basing this claim on a historical 9-dash map which showed it to have such jurisdiction. However, this historical basis has been debated, conflicts with the United Nations Convention on the Law of the Sea (UNCLOS), and in a 2016 decision by the Permanent Court of Arbitration was held to have no legal basis in international law – China claims this decision to be null and void.^[21] China’s main two tactics for furthering their interests in the South China Sea has been their artificial island creation and use of a maritime militia. These tactics have questionable legality under international law and have prompted criticism from other actors in the region. Despite this, these actions have not prompted an outbreak of war. Consequently, they fall within the “grey-zone”.

China's artificial island building is done by dredging up massive amounts of sand and gravel, dumping it on top of pre-existing reefs.^[22] China’s land reclamation in the Spratly archipelago is estimated to have seen more than ten million cubic metres of sand transported to five reefs.^[23] China has created 3,200 acres of new land since 2013 in the South China Sea,^[24] and state media reports that over 5,000 people are stationed at the islands they occupy.^[25] The creation of these islands is not limited to the outskirts of China’s Exclusive Economic Zone (EEZ) and has been largely problematic as it often comes within the EEZ of other states – for example as recently as May 2024 the Philippines noticed signs of land reclamation just 90 nautical miles off their coast (falling within the 200nm EEZ that states enjoy under UNCLOS).^[26]

After creating these islands, China militarises them – radomes, gun turrets and close-in weapon systems for detecting and destroying incoming missiles and aircraft are common features on their artificial islands, and intelligence-gathering and submarine-hunting aircraft have been reported to “frequently operate from the airfield [in Fiery Cross].”^[27] The militarisation of these islands deters access by rival military forces in areas China claims, increases the projection of Chinese power, and allows its armed forces greater room for manoeuvre in the event of a military conflict (e.g. in a potential invasion of Taiwan).^[28]

China has largely avoided directly employing PLA naval forces, instead employing civilian vessels controlled by fishermen to perform duties in disputed waters, “including patrolling, monitoring and attacking foreign fishing vessels.”^[29] These civilian vessels make up China’s maritime militia – they are operated by individuals who do not wear military uniform and also engage in regular fishing activities, blurring the line between military and civilian activities.^[30] So rather than the Chinese government being directly linked to the harassment of foreign vessels and the prevention of access to territorial waters and commercial activities, the civilian-employed maritime militia operates under the pretext that they are acting under their own directive and initiative to enforce maritime law.^[31]

Whilst the maritime militia is not officially linked to any government or state agency, “photos and video, data from ship-to-ship automatic identification systems and other tell-tale behaviour like ‘rafting-up’ by tying multiple boats together” have made it clear they are “organised, funded, and directed by the government of China”.^[32] The goal of the militia is to “establish [Chinese] presence in disputed areas, swarm and overwhelm other claimants’ activities, or reinforce Chinese presence claims under pressure.”^[33]

China has used their maritime militia to take territory from states with competing claims in the South China Sea, employing what Major General Zhang Zhaozhong of the PLA has referred to as the “cabbage strategy”.^[34] This is where the militia, sometimes in conjunction with naval forces will surround a contested area with so many boats that “the island is thus wrapped layer by layer like a cabbage.”^[35]

General Zhang has touted the effectiveness of the cabbage strategy in taking land from the Philippines, saying “for those small islands, only a few troopers are able to station on each of them, but there is no food or even drinking water there. If we carry out the cabbage strategy, you will not be able to send food and drinking water onto the islands. Without the supply for one or two weeks, the troopers stationed there will leave the islands on their own. Once they have left, they will never be able to come back.”^[36]

The cabbage strategy was used in March 2021, when 220 Chinese fishing vessels anchored near Whitsun Reef, which belongs to the Philippines. The ships cited “rough weather” as their reason for anchoring. However, once surrounded China implemented an Anti-Access/Area Denial (A2/AD) strategy to effectively gain control of the territory.^[37]

The cabbage strategy has also been used by other Chinese paramilitary forces such as the Chinese coast guard, who, in May 2013, went beyond the traditional mandate for a state’s coast guard by surrounding and blocking supplies to the BRP Sierra Madre, a grounded Philippines ship which now serves as a makeshift military base in the Second Thomas Shoal.^[38] China has since continued a blockade around the base to prevent the ship from being repaired, in the hopes that the Philippines will eventually be forced to abandon using it as a base and retreat from the area.^[39]

China has also used its maritime militia outside of cabbage strategy missions. The militia is known to harass vessels belonging to other states to make China’s presence known, test the willingness of other states to respond, and potentially push the vessels of other states out of the region.^[40] In 2014, the HD-981 incident occurred, whereby the maritime militia (made up of coast guard vessels, transport ships, tugboats, and fishing vessels) was accompanied by naval ships to escort an oil rig from the China National Offshore Oil Corporation to waters falling within Vietnam’s EEZ.^[41] The move prevented Vietnam’s fishing vessels from fishing in their traditional fishing grounds within Vietnam’s EEZ and allowed China to exploit Vietnam’s EEZ for their own gain.^[42]

China’s actions have prompted the cooperation of other states in the region to counter-balance China’s influence - the Philippines and Vietnam have grown closer together to condemn China, and both are increasing their own artificial island construction (within their own EEZs).^[43] Vietnam added more than 692 acres of land between November 2023 and June 2024, which is more than they had added in the previous two years combined.^[44]

Even as Vietnam increases their artificial island building in the South China Sea, the Philippines has been content with this expansion, Philippine Navy Commodore Roy Vincent Trinidad stating, “Vietnam does not initiate illegal, coercive, aggressive and deceptive actions against us, unlike China.”^[45] This sentiment was also echoed by Philippine Coast Guard Commodore Jay Tarriela, saying that Vietnam does not “engage in harassing our fishermen or illegally deploying coast guard vessels and maritime militia in the waters surrounding our occupied maritime features.”^[46]

China’s grey-zone activity in the region has also prompted response from the US, who has conducted Freedom of Navigation Operations (FONOPS) in the region to maintain a steady presence and deter China’s accumulation of gains.^[47] China has condemned this and claimed the US cannot conduct military operations in its EEZ, however the US has noted that they have every right to do so under UNCLOS.^[48]

Additionally, to defy China’s assertions that they have sovereign airspace above their artificial islands, the US flew B-52 bombers over Chinese artificial islands in December 2015.^[49]

• Gunboat diplomacy
• Proxy war
• Chinese salami slicing strategy
• Unrestricted Warfare

• Layton, Peter (2021). China's Enduring Grey-Zone Challenge (PDF) (Online PDF). Air and Space Power Centre. ISBN 9781925062502.