Civil war continues to envelope Syria as international attempts to resolve the situation continually fail. Some weeks back I addressed the legality of any intervention in Syria and concluded that no such action would be legal. My analysis was limited to the application of the oft-cited doctrine of the Responsibility to Protect. Now, however, there is a new factor in play that could change the equation on intervention.
Ever since the beginning of the Syrian conflict, tensions have been growing between the Assad regime and its northern neighbor Turkey. Recently the tensions have lead to reprisal by Turkey for shells landing on her territory from Syria. The Turkish Chief of Staff even said that future responses would be “even stronger” to any future shelling incidents. Should an armed conflict develop between the two countries it is likely that Turkey will be viewed by the international community as the victim and so entitled to respond. If this were to happen, the door would be open to multi-lateral intervention in Syria under the rubric of collective self-defense. The question would therefore be what the legal scope of any such action would be. The legal framework on the use of force will shed some light on this issue.
The legal discipline of ius ad bellum or the recourse to armed force is currently governed by article 2(4) of the United Nations Charter. It reads in pertinent part,
All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations.
This of course leaves open the possibility of self-defense as it is contained in article 51 of the Charter, which reads,
Nothing in the present Charter shall impair the inherent right of individual or collective self-defence (sic) if an armed attack occurs against a Member of the United Nations, until the Security Council has taken measures necessary to maintain international peace and security. Measures taken by Members in the exercise of this right of self-defence (sic) shall be immediately reported to the Security Council and shall not in any way affect the authority and responsibility of the Security Council under the present Charter to take at any time such action as it deems necessary in order to maintain or restore international peace and security.
The resulting discipline is triggered by an “armed attack”, without which there can be no legal recourse to self-defense. Some argue, and not without good reason, that an immanent attack is sufficient to trigger a targeted State’s right to self-defense and that there is no need to wait until the violence of an armed attack is actually unleashed. In any case, the situation on the Syria-Turkey border and it currently escalating violence seem to remove any need to rely on such a doctrine.
Another cornerstone of the doctrine of self-defense is that any action must be proportionate to the threat that it is meant to shield against. It must also be done out of necessity and designed to put an end to the threat, not as a form of punishment for the attack. What then would be the proportional response given the current situation? History provides good reason to believe that only limited action would be appropriate and that it would have to fall short of regime change.
One useful example is the 1967 Arab-Israeli War which provides an example of the limits of self-defense when it comes to intervention in surrounding hostile States. Israel (after launching an anticipatory attack) took control of the West Bank from Jordan, the Sinai Peninsula from Egypt and the Golan Heights from Syria. There was no attempt (likely would have been futile anyway) to take over or overthrow the governments of the attacking parties. Again here, the response was limited to securing territory to make sure the enemy could not launch new attacks. It is not my intention to enter into the merits of the war, but only to point out the limit of the response.
Another example is the 1991 Gulf War in response to the Iraqi invasion and occupation of Kuwait. The United States and her allies (who took action on the UN mandate) did not take over the country and overthrow the regime. This was in part because the collective action had achieved its stated goals by expelling the invaders and creating the conditions (such as a no-fly zone) to prevent a reoccurrence of the violence. There was no need to take over the country. If a response by the international community to a complete invasion fell short of regime change, in part because such a response would be disproportionate, then such a response to border clashes would also seem to be inappropriate. This would bring us to the conclusion that any defensive action taken by Turkey (and her allies) would therefore be limited to ensuring the protection the border areas.
The normative picture is not so clear however. The American invasion of Afghanistan (and the eventual overthrow of the Taliban regime) was in part justified based on the right to self-defense. If such an action were acceptable it would then be arguable that a more robust reaction to Syrian border incursions could be justified as self-defense. One argument could be that a greater involvement in the conflict is the only way to ensure that the attacks do not continue without unnecessarily prolonging the conflict.
Right now the international community is playing a dangerous game of chicken with the Syrian Civil War. On one hand there are States that do not want to see another intervention and regime change as happened in Libya. On the other hand there are States that are just looking for an excuse either to flex some muscle or push forward the Arab Spring. Unfortunately, innocent people are caught in the middle of this high stakes political struggle. Self-defense may be a mechanism to put an end to this continuing conflict. Something needs to be done, and as has been acknowledged, the current attempt to calm the situation is failing miserably.
 The former envoy, Kofi Annan, called his mediation efforts “Mission: Impossible”. See, Rick Gladstone, Veteran Algerian Statesman to Succeed Annan as Special Syrian Envoy, NYT, 17 August 2012.
 Of course, it is likely that any action by Turkey will be seen as illegitimate by those countries that support the Assad regime or at least are against any intervention in this as-to-now internal conflict.
 Turkey is a member of the North Atlantic Treaty Organization (NATO). Per the North Atlantic Treaty, an attack on any single member is an attack on all members necessitating collective action in self-defense. See, Article 5 (“The Parties agree that an armed attack against one or more of them in Europe or North America shall be considered an attack against them all and consequently they agree that, if such an armed attack occurs, each of them, in exercise of the right of individual or collective self-defence (sic) recognised (sic) by Article 51 of the Charter of the United Nations, will assist the Party or Parties so attacked by taking forthwith, individually and in concert with the other Parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area.”)
 On this point see, Natalino Ronzitti, Diritto internazionale dei conflitti armati, p. 38 (Torino 2001), citing, ICJ, Nicaragua v. United States, 1986 Reports 103.
 This is often based on the “Caroline Affair” and the resulting doctrine of preemptory self-defense. The incident arose out of the British destruction of an American ship in New York State that was being used to supply rebels in British Canada. See, Moore, A digest of international law as embodied in diplomatic discussions, treaties and other international agreements, vol. 2, at pp. 409-410 (1906). Others point to the 1967 Arab-Israeli War and the preemptive strike of Israeli forces against the Egyptian air force. On the extreme, some make mention of the 2003 invasion of Iraq as preventative self-defense.
 As noted, Israel attacked first, however this is generally understood as an example of anticipatory self-defense al a Caroline.
 UN Security Council Resolution 678 (1990).
 Admittedly, this argument has been criticized. See i.e., Jonathan I. Charney, The Use of Force Against Terrorism and International Law, 95 A.J.I.L. 835 (2001)