A Legal Assessment of North Korean Missile Tests


| Aug 11, 2023

Missile North Korea

On July 11, 2023, the Democratic People’s Republic of Korea’s (DPRK) Korean People’s Army (KPA) Strategic Force fired a Hwasong-18 intercontinental ballistic missile (ICBM), North Korea’s most powerful ballistic missile, a distance of some 3,800 miles, with most of the flight occurring in outer space. Seventy-four minutes later, the missile re-entered earth’s atmosphere and landed in the Sea of Japan. A statement by the G-7 claimed the missile landed in Japan’s exclusive economic zone (EEZ), although Japan’s Ministry of Defense did not confirm this. The test reportedly was designed to “put the United States within range.” According to Professor Jeffrey Lewis, an expert on North Korea’s nuclear program, it represented a “huge leap in the North’s nuclear capabilities.”

Between 18 and 24 July, the KPA Strategic Force fired four additional ballistic missiles that also landed in the Sea of Japan. North Korea apparently did so in response to the USS Kentucky (SSBN-737) surfacing in Busan, South Korea, on 18 July and USS Annapolis’s (SSN-760) visit to Jeju Naval Base three days later. USS Kentucky’s port call was especially noteworthy as it was the first visit by a nuclear-powered ballistic missile submarine to South Korea in four decades. The USS Annapolis is a nuclear-powered attack submarine that does not carry ballistic missiles.

Global condemnation quickly followed the missile launches. UN Secretary-General Antonio Guterres denounced the first Hwasong-18 launch and called on North Korea to “comply with its international obligations.” Guterres had previously described North Korean missile tests as “clear violations of international law.” Likewise, the G-7’s foreign ministers released a statement condemning North Korea’s “unlawful nuclear and ballistic missile capabilities.” And the White House described the missile tests as “destabilizing” and “unlawful.”

Such North Korean missile tests violate international law, but it is not always clear why that is the case. In this post, we briefly examine the history of North Korea’s nuclear and ballistic missile programs, touching on its sporadic participation in non-proliferation talks and treaties. Next, we catalog the UN Security Council Resolutions prohibiting North Korean nuclear and ballistic missile tests. Finally, we explain how treaties and customary international law regulate missile tests at sea, in airspace, and in outer space. We conclude that in addition to violating a series of binding UN Security Council Resolutions, the most recent North Korean missile tests, and many of those that preceded them, violated the international legal obligation of “due regard.”

North Korea’s Nuclear and Ballistic Missile Programs

North Korea’s nuclear aspirations emerged in the 1950s when the Soviet Union and DPRK signed two agreements on cooperation in nuclear research projects. The cooperation bore fruit when North Korea constructed a nuclear reactor at Yongdong with Soviet aid in the 1960s, which was expanded in the following decades with Soviet and Chinese assistance. By the end of the 1970s, the DPRK had launched a nuclear weapons development program intended, in great part, to contain Japan. As the Congressional Research Service noted in July 2023, North Korean leader Kim Jong Un now sees his country’s expanding nuclear program as the “ultimate guarantor of his autocratic rule.”

North Korean nuclear development has been characterized by legal whiplash. In 1985, it acceded to the Non-Proliferation Treaty (NPT), and in 1994 the United States and North Korea reached a bilateral agreement by which North Korea committed to freezing its plutonium weapons program. However, North Korea withdrew from the NPT in 2002 after the United States discovered it was enriching uranium in violation of the NPT. The U.S.-DPRK framework collapsed, and North Korea expelled International Atomic Energy Agency inspectors. But soon thereafter, North Korea agreed to participate in negotiations with South Korea, China, Japan, Russia, and the United States – the so-called Six-Party Talks. It withdrew from them in 2009 and restarted its plutonium-producing facilities. Between 2006 and 2017, North Korea detonated nuclear devices on six occasions.

As Alexandre Mansourov has explained, “From the beginning, the military application of the [North Korean] nuclear program was coupled with the missile development program.” Since the mid-1980s, when it reverse-engineered a Soviet Scud-B missile, North Korea has launched, or attempted to launch, hundreds of ballistic missiles with the ability to deliver nuclear weapons. In the last two years alone, it tested over 80 short, medium, intermediate, and intercontinental-range missiles from various facilities. The Korean People’s Navy has also demonstrated the capability to fire submarine-launched missiles.

UNSC Resolutions Prohibiting North Korea’s Programs

North Korea’s nuclear weapon and ballistic missile programs are significant sources of instability that, as discussed below, have prompted more than two dozen UN Security Council Resolutions. Unfortunately, “deep divisions” have recently precluded further collective action by the Council. For example, when the United States introduced a draft Security Council Resolution in response to a March 2022 North Korean ICBM test, China and Russia exercised their veto power. Unfortunately, there is little prospect of a Security Council response to the most recent tests.

In July 2006, North Korea violated a self-proclaimed moratorium on testing ballistic missiles by firing at least six missiles, including a long-range Taepodong, into the Sea of Japan. Ten days later, the Security Council reacted by unanimously passing Resolution 1695 – a “demand that the DPRK suspend all activities related to its ballistic missile programme” and a legal authorization for Member States to “prevent missile and missile-related items, materials, goods, and technology being transferred to DPRK’s missile or WMD programmes.”

Undeterred, North Korea conducted its first nuclear test in October 2006.  The Security Council, acting under Chapter VII of the UN Charter, responded by unanimously adopting Resolution 1718. It condemned the nuclear test and demanded, inter alia, that North Korea refrain from further nuclear or ballistic missile tests. The resolution also called on North Korea to return to the NPT, directed it to suspend all ballistic missile activities, and insisted that it abandon its nuclear program in a “complete, verifiable, and irreversible manner.” Since the passage of Resolution 1718, North Korea has been under constant UN sanctions, although not all countries have enforced them effectively. The sanctions include trade embargoes, an arms embargo, shipping restrictions, a ban on the sale of luxury goods, financial sanctions, and diplomatic sanctions.

After North Korea’s second nuclear test in May 2009, the UN Security Council unanimously adopted Resolution 1874, which reiterated many of Resolution 1718’s provisions, including the demand that North Korea refrain from additional nuclear and ballistic missile tests. The resolution also called for North Korea to join the Comprehensive Nuclear Test Ban Treaty, which it has not yet signed or ratified.

In January 2013, the UN Security Council unanimously adopted Resolution 2087 following a December 2012 North Korean satellite launch. It demanded that North Korea not proceed with further launches using ballistic missile technology. Two months later, the Security Council reacted to North Korea’s third nuclear test by unanimously adopting Resolution 2094, which reiterated the condemnation of ongoing nuclear and ballistic missile programs, as well as the ban on further missile tests. Unlike prior resolutions, Resolution 2094 explicitly mentioned North Korea’s uranium enrichment efforts in its condemnation.

After North Korea defiantly conducted a fourth nuclear test in January 2016, the Security Council unanimously adopted Resolution 2270. It reaffirmed that North Korea must not conduct further ballistic missile or nuclear tests. Additionally, the Security Council directed North Korea to abandon all chemical and biological weapons and programs and act in accordance with the Biological Weapons Convention and the Chemical Weapons Convention. Following another nuclear test in September of that year, the Security Council unanimously adopted Resolution 2321. Like earlier resolutions, it reaffirmed that “the DPRK shall not conduct any further launches that use ballistic missile technology, nuclear tests, or any other provocation.”

Two ICBM tests in July 2017 led the Security Council to adopt Resolution 2371 unanimously. The resolution reiterates the demands of previous resolutions: “The DPRK shall not conduct any further launches that use ballistic missile technology, nuclear tests, or any other provocation,” and it “shall suspend all activities related to its ballistic missile program and in this context re-establish its pre-existing commitments to a moratorium on missile launches.” Following a sixth nuclear test two months later, the Security Council unanimously adopted Resolution 2375, which yet again echoed previous resolutions’ demands. And in December, it unanimously adopted Resolution 2397 in response to a November ICBM launch. Resolution 2397 essentially repeats prior condemnations and demands.

As a UN Member State, the aforementioned resolutions legally bind North Korea (see UN Charter, art. 25). Therefore, all the North Korean ballistic missile launches were “internationally wrongful acts” under international law (Articles on State Responsibility, art. 2). Note that U.S. Indo-Pacific Command (INDOPACOM) maintains an Enforcement Coordination Cell hosted by the Seventh Fleet that facilitates multinational enforcement of maritime sanctions, including those imposed by these resolutions (on maritime interdiction of North Korean ships, see here by James Kraska).

The International Laws Applicable to Ballistic Missile Tests

As noted in the introduction, the Japanese Ministry of Defense has not confirmed reports that the missile involved in the most recent tests landed in Japan’s EEZ. But North Korean missiles unquestionably have landed in Japan’s EEZ in the past (see also, e.g., here and here). And just last month, Russia investigated whether a North Korean test missile landed in its EEZ. Additionally, North Korea has tested missiles that traverse outer space (sometimes as they overfly Japanese territory) before re-entering the atmosphere. Notwithstanding the unambiguous violation of the aforementioned Security Council Resolutions, these and similar North Korean missile tests raise the question of whether the flight path or impact location of the missiles affect their status under international law.

Generally speaking, weapons testing of missiles in or through the so-called “global commons” does not violate international law on the basis of location. The commons include the high seas, international airspace, and outer space (on the EEZ, see below). High seas are waters seaward of an EEZ or of the territorial sea (or archipelagic waters) if a coastal State does not claim an EEZ (Law of the Sea Convention (LOSC), art. 86). International airspace is all airspace beyond that above a State’s territorial sea or land, which is “national airspace” (DoD Law of War Manual, § 14.2.1). And although the legal demarcation of outer space has been controversial for many decades, the various approaches to the matter generally result in a demarcation line between 80 and 120 kilometers above earth (Tallinn Manual 2.0 at 271). Most States have yet to express a firm position on the matter (Commander’s Handbook on the Law of Naval Operations, NWP 110-14M, § 1-10).

In the commons, States may engage in military activities so long as there are no specific rules of international law precluding the activity, such as the prohibition on using force (UN Charter, art. 2(4)), and they are conducted with “due regard” (see below) for the right of other States to use the area concerned for lawful purposes (the “high seas” freedoms, LOSC, art. 87). Except for special prohibitions on weapons testing in Antarctica and on the Moon (Antarctic Treaty, art. 1(1); Moon Agreement, art. 3(4)), which are not subject to any State’s sovereignty, permissible national activities include weapons testing such as missile launches from, through, or into the commons.

With respect to the North Korean missile launches, it is, therefore, generally the “due regard” rule that determines whether tests into or through the commons are lawful. Due regard denotes conducting one’s activities in a manner that does not interfere with the safety or rights of other States, the most important of which is safe navigation through the area concerned.

This is a customary law obligation applicable throughout the commons. It also appears in various treaties. For instance, Article 3(d) of the Chicago Convention on International Civil Aviation requires State aircraft to operate with “due regard for the safety of navigation of civil aircraft.” Article 87(2) of the Law of the Sea Convention provides that high seas freedoms, which include navigation and overflight, “shall be exercised by all States with due regard for the interests of other States in their exercise of the freedom of the high seas.” And Article IX of the Outer Space Treaty notes,

In the exploration and use of outer space, including the Moon and other celestial bodies, States Parties to the Treaty shall be guided by the principle of cooperation and mutual assistance and shall conduct all their activities in outer space, including the Moon and other celestial bodies, with due regard to the corresponding interests of all other States Parties to the Treaty.

North Korea is not a Party to the Law of the Sea Convention but is Party to the Chicago Convention and Outer Space Convention. Because the due regard obligation is customary in character, it binds North Korea throughout the commons irrespective of whether the treaty provisions in question bind North Korea at all, or in the attendant circumstances.

Moving landward, a coastal State enjoys certain exclusive sovereign rights and jurisdiction over the living and non-living resources in the EEZ. But the coastal State EEZ rights enumerated in Article 56 of the Law of the Sea Convention do not include security interests. The result is that, in practical terms, the EEZ is subject to the same navigational regime as the high seas for military purposes so long as other States pay due regard to the coastal State’s EEZ rights (LOSC, arts. 58(1) & (3)). Thus, “[s]ince all ships and aircraft, including warships and military aircraft, enjoy the high seas freedoms of navigation and overflight and other internationally lawful uses of the sea related to those freedoms…in and over those waters,” military activities falling short of the “use of force” (UN Charter, art. 2(4)) against the coastal State are lawful, so long as they do not unduly interfere with the coastal State’s prerogatives in the EEZ (Commander’s Handbook, § 2.6.2). Such military activities include missile testing.

We acknowledge that eighteen States claim the right to regulate or prohibit foreign military activities in the EEZ. However, as Professor Pete Pedrozo has explained (p. 524), such claims are unlawful, a position long-maintained, and appropriately so, by the United States. Among the unlawful constraints he cites are “restrictions on ‘non-peaceful uses’ of the EEZ without consent, such as weapons exercises,” and “restrictions on navigation and overflight through the EEZ.” Missile tests would be encompassed in both. Accordingly, Japan and other affected States cannot claim that North Korean missile testing into their EEZ is unlawful simply because it affects their security interests.

Although military activities like missile tests are not prohibited in the EEZ, they must be conducted, as in the commons, with due regard for other users of the zone, including the coastal State’s exercise of sovereign rights and jurisdiction over the resources therein. Therefore, systems have been established to warn other users of military activities that might pose a particular risk in the shared space (see, e.g., Pedrozo, p. 535-36). In particular, North Korea is a member of the International Civil Aviation Organization and the International Maritime Organization and is accordingly obligated to issue NOTAMs and NOTMARs respectively, when appropriate (see examples here and here).

And with respect to military activities, the Navy/Marine Corps/Coast Guard’s Commander’s Handbook on the Law of Naval Operations (§ explains,

Any State may declare a temporary warning area in international waters and airspace to advise other States of the conduct of activities that, although lawful, are hazardous to navigation and/or overflight. The United States and other States routinely declare such areas for missile testing, gunnery exercises, space vehicle recovery operations, and other purposes entailing some danger to other lawful uses of the seas by others. Notice of the establishment of such areas must be promulgated in advance in the form of a special warning to mariners, notice to mariners, notice to airmen, hydro-Atlantic/hydro-Pacific messages, and the global maritime distress and safety system.

Ships and aircraft of other States are not required to remain outside a declared warning area but are obliged to refrain from interfering with activities therein. Consequently, ships and aircraft of one State may operate in a warning area within international waters and airspace declared by another State to collect intelligence and observe the activities involved, subject to the requirement of due regard for the rights of the declaring State to use international waters and airspace for such lawful purposes (emphasis added). The declaring State may take reasonable measures, including the use of proportionate force to protect the activities against interference.

Analysis of the DPRK Launches

To begin, the North Korean missile launches are not for “lawful purposes” because of the UNSC bans. But putting that fact aside, and while North Korea has issued warnings of satellite launches (see here p. 13), it has not done so for missile launches. This failure presents a significant risk to other States and their vessels and aircraft. For instance, the International Maritime Organization’s Maritime Safety Committee adopted a resolution this June calling on North Korea to comply with its obligations to provide prior warnings of launches and “cease unlawful and unannounced ballistic missile launches across international shipping lanes.” It also requested the organization’s Secretary-General “to take appropriate and practicable actions to establish close and cooperative relationships with relevant other international organizations including the International Civil Aviation Organization, which face the common serious challenges posed by the afore-said DPRK missile launches endangering the safety of international transport.”

To summarize, North Korean missile tests violate UNSC resolutions and therefore are illegal. And while international airspace, the high seas and EEZ, and outer space may, in general, be used for military activities of all States, the tests were conducted in a manner that failed to comply with the obligation to exercise due regard for the rights of other users of these areas. They posed a hazard to safety and potentially infringed on the affected coastal States’ ability to exercise sovereign rights and jurisdiction in the EEZ, as well as the right of all States to use the oceans and international airspace for navigation. A key aspect of that obligation (both treaty-based and customary in character) is the requirement to issue appropriate warnings when missile tests are hazardous to aircraft or vessels, which North Korea did not do.

The only case of a violation by a missile flight based on location alone would be the penetration of (whether through landing or transit through) national airspace, which covers the land territory, archipelagic waters, and territorial seas of another State. Such penetration would violate the sovereignty of the State concerned (LOSC, art. 2). Overflight of a State’s territory through outer space does not, as it is a commons.


North Korean ballistic missile tests are unquestionably prohibited by international law because, since 2006, they have been banned by the UN Security Council. The Security Council has repeatedly reiterated its decisions, condemned North Korea’s provocations, and demanded that the North Korean government refrain from further nuclear and ballistic missile tests. Moreover, North Korean missile tests have violated the international law governing the sea, air, and space domains. Specifically, those tests conducted without adequate due regard for the rights and safety of other States were internationally wrongful acts.


Michael N. Schmitt is the G. Norman Lieber Distinguished Scholar at the United States Military Academy at West Point. He is also Professor of Public International Law at the University of Reading and Professor Emeritus and Charles H. Stockton Distinguished Scholar-in-Residence at the United States Naval War College.

Major John C. Tramazzo is an active-duty Army judge advocate and a military professor in the Stockton Center for International Law in Newport, Rhode Island.


Photo credit: Stefan Krasowski