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North Korean Missiles and the Legal Implications for the United States

By Maximilian Raileanu

Article V of the Treaty of Mutual Cooperation and Security states that “Each Party recognizes that an armed attack against either Party in the territories under the administration of Japan would be dangerous to its own peace and safety and declares that it would act to meet the common danger . . . .” This language dictates that the United States is treaty-bound to respond to an attack against Japan with military force. Up until a few years ago, the concern that this treaty would drag the United States into a war (possibly on a global scale) was nearly non-existent. However, with the stability of the Sea of Japan region in jeopardy, and missiles flying over the Japanese mainland, this concern becomes very real.

North Korea, on its quest to become a nuclear power, has tested fourteen missiles since February 2017. These tests are a direct violation of multiple UN resolutions, but as we have seen, Kim Jong Un is not concerned with the consequences (evidenced by his continued missile tests) of these actions. As frightening as these actions may be, the most concerning event that has taken place is North Korea’s missile test on September 15, 2017, which flew over the Japanese island of Hokkaido. 

This event raises the question: does the United States have an obligation to act under the Treaty of Mutual Cooperation and Security? Observing the applicable language from Article V, the two words to focus on from this section are “attack” and “territories.” In order to answer the question from above, it must be determined whether this incident involved a territory of Japan (an area in which Japan has sovereignty over) and whether this can be considered an attack.

According to international law, a violation of national airspace is a serious breach of sovereignty. Article 3 of the Chicago Convention of 1944 (an international multilateral agreement with 191 signatory countries) states that no state aircraft (defined as military, customs and police services) of a contracting state shall fly over the territory of another state without authorization. North Korea is not a contracting member of this treaty and the term “missile” is not included in the definition of “military aircraft.” However, this could be used as persuasive authority to infer that foreign ballistic missiles being tested for nuclear capability cannot transit through the airspace of another country without authorization.

This leads to the obvious question, did this missile breach Japan’s sovereign airspace above a Japanese territory? The Chicago Convention stated that a country has exclusive sovereignty over the airspace above its territory. CNN reported that the North Korean missile reached a height of 478 miles (770 km) before landing in the ocean. The commonly accepted line between airspace (sovereignty) and outer space is called the Karman line, which states that outer space begins at 100km. While this line is not effectively the law of the international community, it is persuasive in determining whether the North Korean missile passed through Japan’s sovereign airspace over a Japanese territory. That said, while the missile did pass over a territory, it did not pass through sovereign airspace because the missile was at an altitude of 770 km, well over the Karman line. Therefore, this incident did not involve sovereign territory as required by the Treaty of Mutual Cooperation and Security.

The second question to address before concluding whether the US must meet the common threat under the Treaty is determining if this missile flyover can be considered an attack. According to Merriam-Webster Dictionary, an attack is an act of violence against someone or something, often with the intent of trying to hurt, injure, or destroy. While it is possible to make an argument that this flyover was a violent act against Japan, it would be a relatively weak argument. The intention of the flyover was to test North Korea’s ballistic missile program. The international community has categorized this flyover as a test, and the intention cannot be said to have been to hurt, injure, or destroy the people of Hokkaido. In all, this missile test cannot be considered an attack. Because this missile flew over Japanese sovereign airspace, and because the test cannot be considered an attack, the obligations of the United States under the Treaty of Mutual Cooperation and Security are not triggered.

So legally, what can the United States and Japan do about this North Korean missile test? To sum up the answer: nothing. After deciding to withdraw from the Treaty on the Nonproliferation of Nuclear Weapons in 2003, in an attempt to halt North Korea’s nuclear programs, the US, Japan, China, Russia, and South Korea entered into talks with North Korea. These Six-Party Talks resulted in North Korea agreeing in 2005 to abandon all nuclear weapons and nuclear programs. However, these talks broke down in 2009 after North Korea conducted a rocket launch in violation of the talks. This left North Korea free to continue their nuclear program and tests without the possibility of legal reprisal. Therefore, the proper way to respond to this missile test will be up to the governments of these countries and the UN.

Solace can be taken knowing that this missile passed over Japanese sovereign airspace, but if one of these missiles was to land within Japanese sovereign territory, or perhaps fly through Japanese sovereign airspace, the result of this analysis would likely change.


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