Written by Jonathan Worboys* and Laura Edwards**
The first half of 2018 saw a welcome de-escalation of tensions on the Korean Peninsula. In particular, two unprecedented events heightened the anticipation for an official end to the Korean War: the Inter-Korean Summit Meeting at Panmunjeom on April 27, 2018, and the Singapore Summit between the United States and North Korea on June 6, 2018.
These events have catalyzed discussions regarding the establishment of a lasting peace regime for the Korean Peninsula. Recognizing the express intentions of the parties to bring an official end to the Korean War, this article provides initial reflections on and outlines the international law implications of a potential peace treaty for the Korean Peninsula. Furthermore, because peace talks between North Korea, South Korea, and the United States are still in their early stages, this article seeks to highlight some of the critical questions for consideration as the parties try to move toward a fully-formed peace treaty.
What form would an agreement take?
For the past sixty-five years, an armistice agreement has regulated hostilities on the Korean Peninsula. The agreement came into effect in 1953 after it was negotiated by military representatives from the two Koreas, China, and the United States, with the United States representing the United Nations Command. Unlike a formal peace treaty, which officially terminates war, an armistice agreement simply “suspends military operations.”
The Panmunjeom Declaration, signed on April 27, 2018, outlines the intention of the two Koreas to turn the 1953 Armistice Agreement “into a peace treaty.” However, the recent joint statement released by President Donald Trump and North Korea’s Kim Jong Un at the Singapore Summit (Joint Kim-Trump Statement) does not refer specifically to the creation of a “peace treaty,” but rather to a “lasting and robust peace regime.” While the term “treaty” typically denotes an agreement that is binding in international law, states may choose from an array of other instruments, such as a “Memorandum of Understanding,” “Convention,” or “Protocol,” to potentially create legally binding relations. Whether or not an agreement between states is designated a “treaty” is therefore a matter of substance, not just definition.
Although there appears to be some uncertainty about the exact description of the instrument in this case, we expect that the parties will enter into a treaty within the meaning of Article 2(1) of the Vienna Convention on the Law of Treaties (VCLT). Such a treaty would create rights and obligations that are enforceable under international law and potentially possess the endorsement of the UN Security Council as well. This is notwithstanding the fact that North Korea is not a party to the VCLT, as Article 6 of the VCLT affirms that every state possesses the capacity to conclude treaties.
Who would be the parties to a peace treaty?
It is clear that both Koreas would need to be formal parties to the agreement in order to achieve lasting peace. The inclusion of both Koreas should not be treated as a foregone conclusion, however, as North Korea has attempted to exclude South Korea from a peace treaty with the United States on several previous occasions. Nevertheless, both Koreas expressed their intention to work together at the April 2018 Inter-Korean Summit, as the two leaders agreed to convert the Korean Armistice Agreement into a full peace treaty. Subsequently, the parties expressly affirmed this commitment in the Panmunjeom Declaration.
The Panmunjeom Declaration also perceives a direct role for both the United States and China in the peace talks, because it stipulates that the two Koreas will pursue trilateral meetings with the United States, or quadrilateral meetings with the United States and China. Following the Singapore Summit on June 6, 2018, it became even clearer that the parties intend the United States to play a direct role in the peace process, including an eventual peace treaty. The United States has a significant stake in the peace process as well, since it hopes to see an end to North Korea’s nuclear weapons and ballistic missile programs, which pose a grave security threat to both the United States and to key allies in the region. However, as already highlighted, the Joint Kim-Trump Statement that was issued at the conclusion of the Singapore Summit does not make any express reference to a peace treaty per se, nor does it explicitly refer to the role of the United States in this regard.
A conceivable alternative is for the United States to simply endorse an inter-Korean peace treaty without itself becoming a treaty party. The United States has a long history of acting as a witness to such inter-state agreements, including the Algiers Agreement between Eritrea and Ethiopia in 2000, the Itamaraty Declaration of Peace between Ecuador and Peru in 1995, and the Washington Declaration between Israel and Jordan in 1994.
Commentators have also raised the possibility that any government that contributed armed forces to the United Nations Command (“contributing governments”) could have a legitimate claim to be party to a subsequent peace treaty. At the moment, however, this option remains a remote possibility given that the two Koreas have identified only the United States (and possibly China) as legitimate negotiating partners for the peace talks. Since the Panmunjeon Declaration was signed, no contributing governments are known to have expressed an interest in expanding the number of treaty signatories at this time.
What are the possible legal implications of a peace treaty?
As with all inter-state peace agreements, a formal peace treaty is capable of being legally binding and would have the foremost effect of officially terminating the Korean War. Assuming that the terms of the treaty are binding on the same parties to the 1953 Armistice Agreement, a peace treaty may also supersede the agreement by operation of law, or by making the latter obsolete.
A formal peace treaty would also affect the tenuous legal and socio-legal frameworks that have developed since the 1953 Armistice Agreement was originally implemented. For instance, the peace treaty might also regulate the presence of foreign armed forces on the Korean Peninsula. In The Case Concerning Armed Activities, the International Court of Justice highlighted the importance of outlining a modus operandi for military presence in a peace treaty. In particular, a key issue of contention in the case was whether certain provisions of the Lusaka Ceasefire Agreement constituted consent by the Democratic Republic of the Congo to the presence of Ugandan troops in border areas. Neither the Panmunjeom Declaration nor the Joint Kim-Trump Statement makes any reference to troop presence. However, with recent signs that the United States and South Korea plan to halt their joint military exercises, a modus operandi on troop presence may be an especially important consideration when negotiating a peace treaty in this case. 
Beyond use of force and military arrangements, twenty-first century peace treaties also frequently refer to obligations under international humanitarian law. Recent events have already highlighted two important issues relevant to international humanitarian law for a future Korean peace treaty: the return of POW/MIA remains and the reunion of separated families. To further ensure that these obligations are binding on the parties (and perhaps more importantly, observed in practice), the peace treaty may refer to the 1949 Geneva Conventions, which are the central international laws governing states’ actions in war. Specifically, the peace treaty may cite Additional Protocols I and II, which regulate POW/MIA remains and the reunion of separated families, respectively.
At this stage, it is not yet clear whether a Korean peace treaty would also refer to general obligations under human rights law. To date, inter-state peace treaties have rarely featured general human rights commitments beyond the status of the party states’ nationals. Nevertheless, given the particular nature of the human rights situation in North Korea, which has been identified by Human Rights Watch as “one of the world’s most repressive states,” a peace treaty may provide an opportune moment to consider the role of human rights commitments in inter-state peace agreements. Such obligations could, for example, commit North Korea to engaging more closely with the United Nations human rights mechanisms, possibly by taking action on the findings of the 2014 UN Commission of Inquiry Report. Other pertinent commitments may also include obligations to accept humanitarian aid, to take steps to release prisoners and detainees held for activities that should not be criminalized under international law (e.g. exercising free speech), and to put an end to the involuntary separation of families.
Finally, there remains the critical question of denuclearization in relation to a potential peace treaty. While both the Panmunjeom Declaration and the Joint Kim-Trump Statement refer to “complete denuclearization” of the Korean Peninsula, the complexities associated with achieving this goal are undoubtedly significant.
Although many factors relating to denuclearization and the peace process remain unsettled, a final peace treaty could conceivably refer to North Korea’s ratification of the Treaty on the Non-Proliferation of Nuclear Weapons and any legal obligations that may arise as a result. Leading up to the conclusion of a peace treaty, both sides could also consider working towards a performance-based plan for achieving denuclearization with the possibility of linking denuclearization to other issues of concern, such as the ratification of human rights treaties and the easing of UN Sanctions. Performance-based plans are not new to peace processes, with the most prominent example being the (unimplemented) Performance-based Roadmap to a Two-State Solution to the Israeli-Palestinian Conflict.
Legal validity of a peace treaty and the question of breach.
The final consideration for a potential Korean peace treaty relates to the legal validity of the treaty and the question of breach. It is clear that all parties would be bound to observe their commitments under the peace treaty, in accordance with the principle of pacta sunt servanda.
In order to ensure compliance, a future Korean peace treaty may also consider delegating verification and monitoring functions to members of the international community. Twenty-first century peace treaties frequently delegate such functions to the United Nations in the form of peacekeeping missions, but a growing number of agreements have delegated those duties to other interested parties as well. In the present context, it is likely that any monitoring or verification mission to North Korea would involve the International Atomic Energy Agency and the United Nations.
Regarding treaty breach, international law has clearly established that a breaching party accrues state responsibility. Furthermore, in the event of a treaty breach, the prohibition on the use of force under Article 2(4) of the UN Charter would remain unaffected. In other words, a breach of the peace treaty could not, under any circumstances, lead to the use of force to ensure compliance with it.
This article has outlined some initial reflections on a potential peace treaty for the Korean Peninsula.
There is no doubt that the treaty we have contemplated here would have a profound impact on the international peace regime, with the potential of bringing stability to both the Korean Peninsula and the greater East Asia region. While the prospect of a peace treaty has only just begun to develop, this article highlights some preliminary considerations from an international law perspective, including the form of the agreement, the parties involved, possible legal implications, and the issue of breach.
First, with respect to form, any agreement would likely be a treaty within the meaning of Article 2(1) of the VLCT and international law would apply. Second, with respect to the parties, both Koreas, the United States, and China could all play a role as formal signatories, but there remains the possibility of a purely inter-Korean treaty. Third, as the discussion above outlined, there are several possible legal implications of a binding agreement, including the treaty’s foremost effect of terminating the Korean War and superseding the 1953 Armistice Agreement. The legal consequences of denuclearization, international humanitarian law, and human rights law also all ought to be considered and will undoubtedly be affected by an inter-state treaty.
Finally, all parties to the treaty would be legally obliged to respect their commitments in accordance with the principle of pacta sunt servanda. A breach of the treaty would likely entail state responsibility, but a breach could not, under any circumstances, justify the use of force to ensure compliance with the treaty.
* Barrister and visiting lecturer in public international law at King’s College London, former Assistant Legal Adviser at the Foreign & Commonwealth Office.
** Legal consultant specializing in mediation, peace processes and government advisory work.
 Agreement Concerning a Military Armistice in Korea, July 27, 1953, T.I.A.S. No. 2782, 4 U.S.T. 234.
 Hague Convention (IV) Respecting the Laws and Customs of War on Land art. 36, Oct. 18, 1907, 36 Stat. 2227; Hague Convention (II) with Respect to the Laws and Customs of War on Land art. 36, July 29, 1899, 32 Stat. 1803.
 Panmunjeom Declaration for Peace, Prosperity and Unification of the Korean Peninsula, (Apr. 27, 2018), full text at http://english1.president.go.kr/BriefingSpeeches/Speeches/32 [hereinafter Panmunjeom Declaration].
 Id., art. 3(3).
 Joint Statement of President Donald J. Trump and Chairman Kim Jong Un at the Singapore Summit, para. 2 (June 6, 2018), full text at http://www.whitehouse.gov/briefings-statements/joint-statement-president-donald-j-trump-united-states-america-chairman-kim-jong-un-democratic-peoples-republic-korea-singapore-summit/ [hereinafter Joint Statement].
 Vienna Convention on the Law of Treaties art. 2(1), opened for signature May 23, 1969, 1155 U.N.T.S. 331.
 Anthony DiFilippo, North Korea’s Denuclearization and a Peace Treaty, 7 North Korean Rev. 1, 7-8 (2011).
 Panmunjeom Declaration, supra note 3, art. 3(3).
 Patrick M. Norton, NAPSNet Policy Forum Online #2 — Norton, “Ending the Korean Armistice,” Nautilus Inst. for Security & Sustainability: NAPSNet Pol. F. (Mar. 29, 1997), http://nautilus.org/napsnet/napsnet-policy-forum/napsnet-policy-forum-online-2-norton-ending-the-korean-armistice/.
 Agreement between the Government of the State of Eritrea and the Government of the Federal Democratic Republic of Ethiopia (Algiers Agreement), Dec. 12, 2000, 40 I.L.M. 260.
 Declaración de paz de Itamaraty, Ecuador-Peru, Feb. 17, 1995, full text at http://peacemaker.un.org/ecuadorperu-itamaratydeclaration95.
 Washington Declaration, Jordan-Isr., July 25, 1994, full text at http://www.kinghussein.gov.jo/w-declaration.html.
 Norton, supra note 10.
 Martin Wählisch, Peace Settlements and the Prohibition of the Use of Force, in The Oxford Handbook of the Use of Force in International Law, 964 (Marc Weller ed., 2017).
 Norton, supra note 10; see also Vienna Convention on the Law of Treaties, supra note 6, art. 59.
 Wählisch, supra note 15, at 966.
 Case Concerning Armed Activities on the Territory of the Congo (Dem. Rep. Congo v. Rwanda), Judgment, 2005 I.C.J. 168 (Dec. 19).
 Wählisch, supra note 15, at 966.
 Case Concerning Armed Activities on the Territory of the Congo, 2005 I.C.J. at 211.
 Reuters, US, South Korea Agree to Suspend Joint Military Exercise, Int’l Bus. Times (June 18, 2018), http://www.ibtimes.com/us-south-korea-agree-suspend-joint-military-exercise-2692215.
 Joint Statement, supra note 5, para. 4.
 Panmunjeom Declaration, supra note 3, art. 1(5).
 Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol I) art. 34, June 8, 1977, 1125 U.N.T.S. 3.
 Protocol Additional to the Geneva Conventions of 12 August 1949, and relating to the Protection of Victims of International Armed Conflicts (Protocol II) art. 4(3)(b), June 8, 1977, 1125 U.N.T.S. 609.
 See, e.g., Framework Agreement on the Status of Nationals of the Other State and Related Matters between Sudan and South Sudan, Sept. 27, 2012, full text at http://peacemaker.un.org/sudansouthsudan-framework-nationals2012.
 Human Rights in North Korea: June 2018 Briefing Paper, Human Rights Watch, http://www.hrw.org/news/2018/06/05/human-rights-north-korea.
 Panmunjeom Declaration, supra note 3, art. 3(4).
 Joint Statement, supra note 5, para. 3.
 A Performance-based Road Map to a Permanent Two-State Solution to the Israeli-Palestinian Conflict, Apr. 30, 2003, full text at http://2001-2009.state.gov/r/pa/prs/ps/2003/20062.htm.
 Wählisch, supra note 15, at 986.
 Id. at 976.