Turkey’s ongoing military action in Syria, Operation Peace Spring, has caused consternation and dismay among its allies. French President Emmanuel Macron warned that the intervention could create an “unbearable humanitarian situation” and demanded that the offensive should cease. In a phone call with Turkish President Recep Tayyip Erdoğan, German Chancellor Angela Merkel called for an immediate end to military operations. British Prime Minister Boris Johnson and U.S. President Donald Trump expressed their serious concern over Turkey’s action and the risk of a humanitarian catastrophe in the region.

Others have gone further. Writing shortly before Operation Peace Spring commenced, U.S. Senator Lindsey Graham promised to “introduce bipartisan sanctions against Turkey if they invade Syria” and to “call for their suspension from NATO if they attack Kurdish forces who assisted the U.S. in the destruction of the ISIS Caliphate.” Echoing these sentiments, Representative Eliot L. Engel, Chairman of the House Foreign Affairs Committee, suggested that the United States should consider kicking Turkey out of NATO. On Oct 13, U.S. Defense Secretary Mark Esper revealed that he warned Turkey in advance of its incursion that if it were to proceed with the operation, this would “damage U.S. relations with Turkey, their staying in NATO.”

We are not in unchartered territory. Demands to suspend Turkey’s membership in NATO, or to expel it from the Alliance altogether, have been made before, including in response to the political crackdown of 2016 and its decision to acquire the Russian S-400 air defence system.

No Suspension Provision in the North Atlantic Treaty

Yet matters are not quite so simple. The founding instruments of many international organizations provide for the suspension of a member State’s rights, and even for the termination of its membership, in certain circumstances. Instruments of this kind include the United Nations Charter (Articles 5 and 6), the Statute of the Council of Europe (Article 8) and the Treaty on European Union (Article 7). Alas, the North Atlantic Treaty is not among them. No provision in the treaty foresees the suspension of membership rights, let alone the expulsion of an ally.

Within NATO, concerns over the behaviour of individual allies are thus resolved primarily through diplomatic means, political pressure, and by taking a long-term view. As Jorge Benitez of the Atlantic Council think tank in Washington put it, NATO leaders tend to “wait out the misbehaving national leaders until a government consistent with alliance values eventually returns to power.”

This has not stopped speculation as to whether a nation may nevertheless be expelled from NATO and if so, how. Indeed, what are the options in the absence of a formal process for suspending or terminating membership?

It is important to bear in mind that NATO is not merely a community of interests, but also a community of values. Inspired by the wording of the Brussels Treaty of 1948, the preamble to the North Atlantic Treaty makes this point in the following terms:

The Parties to this Treaty reaffirm their faith in the purposes and principles of the Charter of the United Nations and their desire to live in peace with all peoples and all governments.

They are determined to safeguard the freedom, common heritage and civilization of their peoples, founded on the principles of democracy, individual liberty and the rule of law. They seek to promote stability and well-being in the North Atlantic area.

They are resolved to unite their efforts for collective defense and for the preservation of peace and security. They therefore agree to this North Atlantic Treaty.

That the Alliance is based on a set of shared values is further underlined by Article 2 of the treaty, which commits the parties to “strengthening their free institutions” and “bringing about a better understanding of the principles upon which these institutions are founded,” as well as by Article 10, which stipulates that prospective members need to be in “a position to further the principles of this Treaty” in order to accede to it.

More Than a Military Alliance

Some of NATO’s founding members sought to accord these principles even greater weight. More than any other party, Canada from the very beginning wished for the North Atlantic community to be “much more than a military alliance” (Memorandum by Assistant Under-Secretary of State for External Affairs, June 26, 1948, in CDER vol. 14, page 521). This desire led the Canadian government to propose that the negotiating parties should accept the compulsory jurisdiction of the International Court of Justice for all legal disputes arising between them. Canada’s high regard for the principles of democracy, political liberty and the rule of law also led it to express misgivings over the potential membership of Portugal and Spain. In the end, the strategic reasons for inviting Portugal to join NATO as a founding member proved more compelling, while Spain acceded only later, in 1982, after democracy had been restored.

Guided by these ideals, Canada also actively pursued the idea of incorporating an expulsion clause into the draft treaty. The annex to the Washington Paper of September 1948, which contained the first outline of the future agreement, noted the following:

The question of including a provision for disqualification under certain circumstances of any of the signatories from enjoying the benefits of the Treaty requires further consideration.

In the eyes of the Canadian government, the circumstances that might justify the disqualification of a party had to include the “coming into power of a communist-dominated government” in that state (Commentary on the Washington Paper, Dec. 6, 1948). To deal with such an eventuality, Canada proposed a draft provision entitling the North Atlantic Council to suspend or expel a member state from the privileges of membership (Draft North Atlantic Treaty, Dec. 17, 1948).

These proposals met with a lukewarm reception. The general feeling among the other negotiating parties was that it would be a mistake to include any provision in the treaty that would raise questions about the voting procedure in the Council (Canadian Ambassador in the United States to Secretary of State for External Affairs, Jan. 4, 1949, in CDER vol. 15, page 483). The British Foreign Secretary, Ernest Bevin, also thought that any efforts to endow the Council with conciliatory powers should be resisted:

I really do not see any advantage in disputes which we may have in the future with the Americans or indeed with the French being discussed in the open and in the presence of the Italians, the Scandinavians and the Portuguese (Mr. Bevin to U.K. Ambassador to Washington Sir O. Franks , Jan. 12,  1949, in The Brussels and North Atlantic Treaties, 1947-1949, page 334).

The idea to incorporate some kind of suspension and expulsion mechanism into the North Atlantic Treaty was therefore dropped. But this left open the question of how NATO should deal with an ally that went “red” as a result of Soviet subversion.

Options Considered

In a statement to the Senate Committee on Foreign Relations in 1949, then-Secretary of State Dean Acheson took the view that such a nation could be booted out even in the absence of a formalized suspension and expulsion procedure. His comments on the preamble to the treaty merit quoting in full:

This draft, Mr. Chairman, starts out with a preamble, and one of the purposes of this preamble was to see if we could in some way describe a democratic non-Communist country. The purpose of that was, if, for instance, Italy becomes a member of such a treaty and then by any chance should go Communist, a question has arisen in people’s minds about what happens then. You do not want to have provisions in such a treaty saying that you can throw them out, because that indicates you are rather doubtful about them before you start; but if you can describe the sort of objectives that are shared by all of these countries, and one of them should no longer be able to be seeking those objectives, then the basis is laid for a separation.

We think that perhaps that is a little bit of a theoretical thing, because probably the first thing any country would do if it became Communist would be to get out of this. That is the way they proceed. They do not stay in. (The Vandenberg Resolution and the North Atlantic Treaty: Hearings, page 93)

The Senate Committee on Foreign Relations also addressed the matter in its report on the treaty. Once again, the relevant passage is worth quoting in full:

The treaty has been criticized in some quarters because it contains no provision for expulsion or the suspension of rights of a recalcitrant member which might fail to carry out its obligations as a result, for example, of its succumbing to communism. Given the nature of the pact and the close community of interests of the signatory states, the committee believes that such a provision would be both unnecessary and inappropriate. Obviously, however, if a member persistently violates the principles contained in the pact, the other members will no longer be obligated to assist that member. Clearly it would fail “to safeguard the freedom * * *” of its people, “founded on the principles of democracy, individual liberty, and the rule of law” as set forth in the preamble, and to strengthen its “free institutions” as provided in article 2. Presumably it would also decline to participate in “mutual aid” (art. 3), and might well violate its undertakings in article 8 “not to enter into any international engagement in conflict with this treaty.” A country suffering such a fate would be in no position either to carry out its own obligations under the treaty or to expect assistance from the other parties. (The Vandenberg Resolution and the North Atlantic Treaty: Hearings, page 379.)

“Material Breach” under the Vienna Convention on the Law of Treaties

These passages confirm that maintaining and furthering the principles on which the Alliance is based — democracy, individual liberty and the rule of law — forms part of the object and purpose of the North Atlantic Treaty. This, in turn, suggests that a failure to comply with these principles may amount to a material breach of the treaty within the meaning of Article 60 of the Vienna Convention on the Law of Treaties. Pursuant to Article 60, a material breach consists of:

(a)  a repudiation of the treaty not sanctioned by the present Convention; or

(b)  the violation of a provision essential to the accomplishment of the object or purpose of the treaty.

To constitute a material breach pursuant to sub-paragraph (a), the violation of the principles underlying the treaty would have to be so extensive in scope, so severe and so persistent as to effectively “disavow” or repudiate the treaty (cf. Namibia Advisory Opinion, para. 95). Turning to sub-paragraph (b), there can be little doubt that continued compliance with the values set out in the preamble and Article 2 is essential for the accomplishment of the object and purpose of the treaty.

Official statements issued by the member states, including at the Brussels Summit in 2018 and more recently on the occasion of NATO’s 70th Anniversary, repeatedly affirm these principles. A member nation that violated them in a systematic and egregious manner would thus cast doubt on the very resolve of the allies to “unite their efforts for collective defence and for the preservation of peace and security” (preamble, North Atlantic Treaty).

Should the conditions for the existence of a material breach be satisfied, NATO’s member states would be entitled, by unanimous agreement, to suspend the operation of the treaty in whole or in part or to terminate it either in their relations with the defaulting state or among them all (Article 60(2) of the Vienna Convention). For these purposes, a unanimous decision of the North Atlantic Council, excluding the defaulting state, would suffice. No further procedural requirements apply, including those laid down in Article 65 of the Vienna Convention.

Whether or not Turkey is in material breach of its commitments under the North Atlantic Treaty is therefore a question to be determined by the other members of the Council. As Klaus Kress has observed, there is a “very serious possibility that Operation ‘Peace Spring’ could constitute a manifest violation of the prohibition of the use of force.” Coupled with President Erdoğan’s threat to “open the gates” for Syrian refugees to migrate to Europe, a threat fundamentally at odds with the unity and solidarity of the Alliance, characterizing these developments as a material breach is not entirely far-fetched.

In any event, they entitle other NATO nations to suspend or scale back their military cooperation with Turkey, even without declaring Turkey to be in material breach. Although Article 3 of the North Atlantic Treaty commits the parties to maintain and develop their individual and collective capacity to resist armed attack, this obligation is meant to pursue the objectives of the treaty. The duty to develop military capabilities and to cooperate to this end therefore does not override the commitment to further the principles of democracy, individual liberty and the rule of law. A number of Allies, including France, Germany and Norway, as well as official NATO partner Finland, are reported to have suspended the sale of military equipment to Turkey.

Overall, the absence of a suspension and expulsion mechanism in the North Atlantic Treaty does not prevent the North Atlantic Council from suspending or terminating the membership of an ally found to be in material breach of the treaty. However, with the 70th anniversary of the treaty just past, this is a sorry position for the Council to be in by any measure. Suspending, let alone terminating, a nation’s membership of NATO would be an extreme measure to be contemplated only once other attempts to restore unity and respect for the Alliance’s founding principles have been exhausted.

(The views expressed here are the author’s own and do not necessarily reflect those of any organization or institution with which he is affiliated.)

IMAGE: Turkey’s President Recep Tayyip Erdogan arrives for the NATO summit, at the NATO headquarters in Brussels, on July 11, 2018. (Photo by BRENDAN SMIALOWSKI/AFP/Getty Images)