The dividing line between war and peace is blurred. This is one of the messages emerging from the National Security Strategy (NSS) of the United States of America adopted in December 2017. The United States is accustomed to viewing the world through the binary lens of war and peace, yet in reality, warns the new National Security Strategy, international relations is an “arena of continuous competition” (p. 28).
This is not exactly a new theme. The idea that war and peace are relative points on a continuous spectrum of confrontation, rather than mutually exclusive conditions, has become quite popular in recent years. Writing in 2013, General Valery Gerasimov, Chief of the General Staff of the Russian Federation, observed that the 21st century has seen a tendency “toward blurring the lines between the states of war and peace”. Speaking in 2015, Sir Michael Fallon, the former British Secretary of State for Defence, declared that contemporary adversaries are deliberately seeking to “blur the lines between what is, and what is not, considered an act of war”. More recently, Jens Stoltenberg, NATO’s Secretary General, suggested that in the past “it was easy to distinguish whether it was peace or war … [b]ut now there’s a much more blurred line”.
The fluidity of war and peace is central to the vocabulary of “gray zone conflict” and “hybrid warfare”. Both concepts are preoccupied with the strategic challenges that adversaries operating across multiple domains present. The notion of gray zone conflict puts the emphasis on the sphere of confrontation, concentrating on the fact that adversaries operate in the area of ambiguity that lies between the traditional state of war and state of peace (see US SOCOM, The Gray Zone). By contrast, the notion of hybrid warfare emphasises the modus operandi adopted by certain adversaries and competitors, focusing on their use of the full range of military and non-military means in a highly integrated manner (see NATO, Wales Summit Declaration, para. 13).
The new National Security Strategy borrows heavily from both sets of ideas. In a section entitled “Preserve Peace Through Strength”, it makes the following points (pp. 27–28):
[A]dversaries and competitors became adept at operating below the threshold of open military conflict and at the edges of international law. Repressive, closed states and organizations, although brittle in many ways, are often more agile and faster at integrating economic, military, and especially informational means to achieve their goals. They are unencumbered by truth, by the rules and protections of privacy inherent in democracies, and by the law of armed conflict. They employ sophisticated political, economic, and military campaigns that combine discrete actions. They are patient and content to accrue strategic gains over time — making it harder for the United States and our allies to respond. Such actions are calculated to achieve maximum effect without provoking a direct military response from the United States. And as these incremental gains are realized, over time, a new status quo emerges.
The concern that adversaries exploit the dividing line between war and peace in an attempt to shift the balance of power in their favour, employing discrete measures across multiple domains in an integrated design, betrays the fact that the NSS is inspired by the gray zone conflict and hybrid threat debates, even though it does not reference these concepts in express terms.
At the heart of the concerns voiced by the NSS is a very palpable unease about the role of international law. The traditional duality between war and peace has always been more of a legal construct than a reality on the ground. While Grotius may have proclaimed that war and peace admits of no intermediate position, this has not prevented States from conflating the two by carrying out acts of warfare under another name. As Christopher Greenwood pointed out some years ago, formal declarations of war were in fact the exception rather than the rule during the 18th and 19th centuries. Examples abound. In 1840, the British Government instructed its fleet in the Mediterranean to seize all Neapolitan and Sicilian ships in a dispute with the Kingdom of the Two Sicilies over a sulphur monopoly. Major hostilities were averted only through French mediation. It should not come as a surprise therefore that Hague Convention III on the Opening of Hostilities of 1907, which made it compulsory to notify the existence of a state of war, is among the less successful instruments born at the second Hague Peace Conference.
Nonetheless, the Grotian divide between war and peace remains a vital part of the international legal order. Under the United Nations Charter regime, peace is the normal state of affairs in international relations, whilst war is the exception. The use of force is permitted only as a measure of last resort in self-defence (Article 51) or where collective non-forcible measures are inadequate (Article 42). Key to this scheme are the legal thresholds that divide normality from the exception, in particular the notion of “armed attack” in Article 51 of the Charter, which serves as the trigger for the right to use force in self-defence. Similarly, in the neighbouring field of the law of armed conflict, the existence of an armed conflict triggers the right to move from law-enforcement to a more permissive warfighting posture.
According to the National Security Strategy, adversaries and competitors are taking advantage of these legal thresholds by operating below the level that would permit the US and its allies to respond by using force. As one of us has written in greater detail (see Sari, Hybrid Warfare, Law and the Fulda Gap), this creates an asymmetric legal environment where States that continue to abide by the law are placed at a competitive disadvantage against adversaries that exploit legal ambiguities and violate the rules of international law.
This dynamic is clear to see in Article 5 of the North Atlantic Treaty, which stipulates that an armed attack against one or more NATO member States in Europe or North America shall be considered an attack against them all. NATO’s collective security response is thus tied to the threshold concept of an armed attack under Article 51 of the United Nations Charter. The conservative view holds that minor incidents, such as localised fighting on a small scale, do not reach the level of an armed attack, even where they involve some loss of life. By using force below this level of intensity in combination with non-forcible measures, a determined adversary is able to achieve incremental gains without enabling its target to mount a direct military response, as the NSS cautions. The build-up to the conflict between the Russian Federation and Georgia in 2008 demonstrates that such a scenario is not farfetched.
Recognising the risk, NATO has declared itself ready in its Warsaw Summit Communiqué (para. 72) adopted in July 2016 to counter hybrid warfare as part of collective defence, including by invoking Article 5 of the North Atlantic Treaty. From a legal perspective, the Warsaw Communiqué may be read as stating the obvious: should hybrid warfare cross the threshold of an armed attack, it would engage the right of individual and collective self-defence. However, the Communiqué may also be seen as a sign that the Allies are willing to reassess the concept of armed attack in the light of gray zone and hybrid warfare tactics. Three elements stand out in this respect.
First, in the Nicaragua case (para. 191), the International Court of Justice defined armed attacks as the “most grave” form of the use of force. However, a strong current of opinion denies the existence of such a gravity threshold (see Chatham House Principles of International Law on the Use of Force by States in Self-Defence, p. 6). Since low-intensity measures are an integral feature of gray zone conflicts and hybrid warfare, they are likely to amplify these voices. In particular, it is difficult to agree with the Court that the provision of weapons and logistical support to rebels by definition constitutes a use of force of lesser gravity not amounting to an armed attack (Nicaragua, para. 195). Russian intervention in Eastern Ukraine shows that such support can easily reach the scale and destructive effect of a direct attack.
Second, in the Oil Platforms (para. 64) and Armed Activities in the Congo (para. 146) cases, the International Court seemed to accept that a series of incidents which do not rise to the level of an armed attack when taken individually may nevertheless do so when viewed cumulatively. Hybrid warfare involves a deliberate pattern of incidents and therefore are likely to bolster support for this accumulation of events approach.
Third, an armed attack does not have to involve physical destruction and loss of life. The Russian military takeover of Crimea illustrates the point. Although Russian forces were present in Crimea with the consent of Ukraine, their actions manifestly contravened the terms of their presence. As such, they amounted to an act of aggression under Article 3(e) of the Definition of Aggression that gave rise to the right of self-defence (see here), notwithstanding the lack of destruction and loss of life. This suggest that non-violent subversive activities directed against the territorial integrity or political independence of a State which are carried out either by military forces or to complement military activities may be considered as constituent elements of an armed attack.
Lowering the gravity threshold of armed attack, adopting the accumulation of events principle and including non-violent subversive activities integrally linked to the use of force among the elements that may make up an armed attack would go some way towards recalibrating the right of self-defence for the challenges of gray zone conflict and hybrid warfare. However, this does not resolve all difficulties. Gray zone and hybrid threats include a broad range of non-violent activities, such as interference in domestic political processes, information operations and economic pressure. Even a greatly relaxed understanding of armed attack does not cover these activities or if it did, it would hollow out the prohibition to use force in Article 2(4) of the United Nations Charter. In any event, military force is not an effective response to every subversive act. Fighter jets and battle tanks are of little use in confronting passportisation, election meddling or disinformation campaigns. The utility of force in such circumstances is indirect: to deter an adversary by imposing costs. Recall, for example, the US missile strike against Syrian air bases in April 2017. This puts the spotlight on the legality of forcible counter-measures. While the International Court appeared to leave the door open for such action in the Nicaragua case (see para. 210), the International Law Commission declared forcible counter-measures to be unlawful in its commentary to the Articles on State Responsibility (p. 132). Of course, the latter position is only as good as the authorities on which it is based.
This brings us back to a broader question raised by the National Security Strategy. If the line between war and peace is becoming increasingly blurred, as it is widely claimed, what is the appropriate response? “Principled realism”, a term embraced by the NSS to describe its underlying approach (p. 1), may hold the answer. A realist response recognises that law is a domain of competition, an environment where adversaries and competitors advance their own strategic interests. A principled response realises that the rule of law is a value in itself and that international law is not just a constraining factor, but also a strategic enabler. A principled realism demands that nations strengthen their legal resilience to withstand the challenges presented by gray zone conflict and hybrid warfare and to defend the international legal order itself against subversion by States that operate “at the edges of international law”. Consistent with such an approach, efforts to counter gray zone and hybrid threats should not blur the line between war and peace further. This requires a more robust engagement with, not disengagement from, international law.