Is President Trump’s plan for a new domestic missile defense system in violation of the Nuclear Non-Proliferation Treaty or the New START? Does it breach any precedent that has been set with the sensitive nuclear-political balance that has existed since the Cold War? Will the defense system trigger a failure of nuclear deterrence, and are there any international courts, legal bodies, or diplomatic actions that the international community can take to prevent the United States from going forward with the creation of its missile defense system?
Section One: Introduction
Donald Trump’s recent announcement of “Iron Dome for America”—now referred to as a “Golden” Dome—upends established precedent in nuclear politics, and while it may not violate direct aspects of the Nuclear Non-Proliferation Treaty (NPT) or the New START, other countries have already expressed their discomfort with the program. The Iron Dome may cause other states to violate the aforementioned treaties and expand their nuclear arsenals, causing issues within international politics and nuclear deterrence that have persisted since 1945. President Trump puts the United States and other nuclear powers in uncomfortable and unprecedented positions by signing an executive order to create drastically more intense missile defense mechanisms for the U.S, calling into question nuclear treaties that the U.S. has ratified, and potentially catalyzing a resurgence in the global nuclear arms race.
Section Two: Background
Since his first term in office, President Trump has had a volatile and contentious history with nuclear power and relationships with other states’ nuclear programs. In his first term, it was unclear whether President Trump would renew the key non-proliferation agreement between the U.S. and Russia, the New START (Strategic Arms Reduction Treaty). He encouraged powers such as Iran to resume the development of nuclear weapons and only recently restored pressure on Iran’s capacity to obtain a nuclear weapon by signing the National Security Presidential Memorandum (NSPM), calling Iran out for violations of the NPT and saying, “A radical regime like this can never be allowed to acquire or develop nuclear weapons.” There have also been discussions of the U.S. restarting nuclear testing for the first time since 1992, which would be an entirely political move to “demonstrate strength” and is not necessary for actual nuclear testing. Generally, President Trump has been problematic and unpredictable regarding nuclear politics, which raises the question of what his defense goals are for the next four years, and whether they will be permissible under the NPT.
The NPT, created in 1968 and entered into force in 1970, is a treaty that exists with the aim of expanding the non-proliferation of nuclear weapons. The treaty was created by a UN-sponsored committee focusing on disarmament. According to the United Nations, “the NPT has been the cornerstone of [the] global nuclear non-proliferation regime.” In line with experts such as Scott Sagan, the creators of the NPT contend that the way to prevent nuclear warfare is to regulate and decrease the dissemination of nuclear weapons as much as possible. The design of the NPT relies on the cooperation of both nuclear and non-nuclear weapon states. The basis of the treaty is that non-nuclear weapon states should renounce their development or acquisition of nuclear weapons in exchange for nuclear weapon states sharing their nuclear technology for
peaceful purposes, such as energy production. The cornerstone of the treaty is an understanding between nuclear and non-nuclear weapon states.
Historically, the U.S.’s role in the NPT has been important to conflict resolution and international law more generally. While the NPT has not altogether halted nuclear proliferation, it has greatly slowed the spread of nuclear weapons and set precedents for foreign cooperation regarding nuclear weapons, which, during the Cold War, was an extreme concern. In recent developments, President Trump has signed an executive order calling for an “Iron Dome for America.”
Ironically, the Iron Dome for America project shares a name with a defense project that exists in Israel, the original “Iron Dome” system. This defense system was created to defend from short-range rockets, shells, and mortars in 2008. The U.S. based a missile defense shield on Israel’s “Iron Dome” project, known as the SkyHunter missile defense system. These systems are, as they presently exist, not inherently problematic on a world-political stage because they prevent small weapons. Since the 1980s, the missile defense system that has existed within the U.S. has only been large enough to prevent missiles from nations such as North Korea or Iran. The U.S. purposefully elected not to scale these defense frameworks to a degree that would be able to defend the nation from a state such as Russia. This is because, in regard to nuclear theory, “mutually assured destruction” is an extreme deterrent for the use of nuclear weapons. China will not choose to send nuclear weapons to the U.S. because they know that the nuclear weapons will greatly harm the U.S., and the U.S., as a nuclear power with secure second-strike capabilities, will have no choice but to strike China back. This will eventually lead to mutually assured destruction between the two powers.
However, President Trump’s “Iron Dome for America” plan aims to not just deter small missile or rocket attacks. Rather, on January 27th, he prompted Secretary of Defense Pete Hegseth to create new plans for “Defense […] against ballistic, hypersonic, advanced cruise missiles, and other next-generation aerial attacks from peer, near-peer, and rogue adversaries” within 60 days. The creation of this defense technology would largely impact the delicate balance between nuclear powers that currently exist: it could cause the U.S. to “dominate the deterrence spectrum.” Suppose Russia suspects that the potential impact of their nuclear weapons has been reduced. Will they feel more comfortable striking the U.S. or other states with their weapons because there may no longer be clear, mutually assured destruction? More importantly, will this trigger Russia to try and scale up its nuclear programs to innovate around U.S. protection technologies and gain back the power and security nuclear weapons gave them?
The Iron Dome for America plan has already prompted a response from Russia, with a foreign official claiming it would target the ability of Russia and China to exercise nuclear deterrence. She went on to say that it would “hinder the prospects for talks on nuclear arms control” and that “the indicated U.S. approaches will not contribute to reducing tensions or improving the situation in the strategic sphere.” Furthermore, this has left Russia potentially in a place where they may feel as though they have to violate the New START and increase their nuclear arsenal. Even if Russia elects not to violate the treaty, the New START is due for renewal in 2026, and it is possible that if Russia feels threatened, they opt not to renew the treaty, or attempt to negotiate to drastically change the treaty’s terms.
While there are few direct historical examples of a nation’s missile defense policy promoting adversaries to expand their nuclear arsenals, there are certainly examples of nuclear arms races or, more broadly, general defense system development competition. One example is the “shipbuilding arms race” between Germany and the United Kingdom before WWI. A more famous example of a nuclear arms race is the Soviet Union and the U.S. during the Cold War. There was explicit competition in the development of nuclear arsenals, which was only encouraged by the opposing state furthering their development. There was a constant fear that either party would “bolt out of the blue” and strike the other state first just to have a first-strike advantage, catalyzing even more of an emphasis on nuclear development.
Because the advancement of missile defense systems has similar implications for deterrence or the effectiveness of a nation’s nuclear system, it is clear that rapid nuclearization or development of nuclear protection systems are both strategically destabilizing. As a policy brief in Stimson states, “If one nation learns that a rival is rapidly developing systems that could overwhelm or defeat its defenses, a realist response dictates that that nation must do the same to offset any strategic advantage its rival might gain.”
Furthermore, the U.S. aimed to create a missile defense program reminiscent of the Iron Dome during the Reagan Administration. In 1983, President Reagan announced his plans for the “Strategic Defense Initiative” (SDI). The program ended a mere ten years later when President Clinton was elected; however, it prompted similar discomfort from the USSR. A recently declassified paper from the CIA’s internal journal, Studies in Intelligence, states that, “In response to the SDI, Moscow threatened a variety of military countermeasures in lieu of developing a parallel missile defense system.” Additionally, the Soviet General Secretary at the time considered “increasing the number of missiles, reinforcing missile silos to increase their survivability, [and] developing and deploying an underwater missile that would not be affected by the space-based missile shield,” according to the paper. It is clear that the development of the SDI triggered a state of alarm from the USSR, and the whole situation is largely comparable to the present Iron Dome in America.
Section Three: Examination and Application of International Law
Momentarily ignoring the question of the feasibility of the “Iron Dome,” which some argue may prove to be a problem, what are the possible implications for international law, specifically looking at U.S. nuclear treaties? As established earlier, the NPT has been one of the most successful international efforts to prevent the global spread of nuclear weapons. 191 states adhere to the treaty, including five “nuclear-weapon states.” The NPT emphasizes nonproliferation, disarmament, and peaceful uses of nuclear energy. It is worth acknowledging that there are also four known nuclear weapon states that do not adhere to the NPT: India, Pakistan, North Korea, who pulled out of the NPT in 2003, and Israel, who does not acknowledge their possession of nuclear weapons, maintaining a policy of deliberate ambiguity.
The U.S.’s expansion of defense mechanisms is not technically in violation of their NPT agreement to “develop” or “acquire” nuclear weapons. However, it indirectly may trigger other nations to do so because it threatens deterrence and a nuclear balance. This can be seen in the strained relationship between the U.S. and Russia. Although the U.S.’s actions did not directly violate the New START, they are upending a balance that has existed since the Cold War by making a drastic change that could jeopardize nuclear deterrence between the two states, forcing Russia to violate the New START and increasing their nuclear arsenal. Russia’s potential response would be based on strategic necessity rather than a legal requirement. That being said, the legalities are slightly more complicated than stating that the U.S. is outright not in violation of the New START.
Although the New START states that “Current and planned U.S. missile defense programs are not constrained by New START,” this statement is conditional on more information. The treaty’s preamble acknowledges the “interrelationship between strategic offensive arms and strategic defensive arms” but goes on to establish that “current strategic defensive arms do not undermine the viability and effectiveness of the strategic offensive arms of the Parties.” This means that the treaty is contingent on the fact that the strategic defensive arms are not effective enough to defend from large military powers and realign interpolitical military dynamics. The U.S.’s plan to develop weapons that would undermine the viability and effectiveness of the strategic offensive arms of the Parties is an entirely different question, and it could be inferred from the treaty that this development is not permitted. It is unclear whether the U.S. is presently in violation of the New START. Because they currently only intend to develop these systems and have not actually done so, it may be true that they have not yet violated the New START. However, because other states, such as Russia, have begun to feel threatened and anticipate the U.S.’s capabilities to undermine the viability of their weapons’ efficacy, the U.S. may be violating the treaty. Overall, it is clear that the U.S. is certainly disrupting the international order and has the potential to be violating treaties.
Section Four: Discussion of the Legal Question
All this information prompts the question, would there be any way to utilize international law to prevent the U.S. from going forward with this defense expansion, preventing other states from feeling as though they must expand their nuclear arsenals to keep up?
There is a lack of a formal enforcing body within the NPT. The International Atomic Energy Agency (IAEA) exists as a “safeguards system,” meaning that they independently “verify a State’s legal obligation that nuclear facilities are not misused and nuclear material is no diverted from peaceful uses.” Furthermore, part of the NPT is a conference that occurs twice every decade to review the treaty’s effectiveness. Preparations are currently being made for the next conference in 2026. However, the U.S. has not technically violated any aspect of the NPT with the Iron Dome. While it may disrupt international nuclear dealings, it may not fall under the NPT to deal with their actions.
Furthermore, it is worth asking if the question of nuclear weapons falls under customary international law at all. Customary international law contains two main prongs: state practice and opinio juris. For a practice to qualify as an opinio juris and therefore fall under the rule of customary international law, states must follow the practice from a sense of legal obligations. According to a comment on the 1987 Third Restatement in the International Law, Eighth Edition textbook by Allen S. Weiner and Chimène Keitner, “a practice that is generally followed but which states feel legally free to disregard does not contribute to customary international law.” The International Court of Justice (ICJ), the dispute resolution body for the UN, was called upon by the UN General Assembly to examine whether nuclear weapons qualified as an opinio juris. Some states referenced the non-use of nuclear weapons since 1945 as a legal acknowledgment by nuclear weapon states. However, other states claimed that the use of nuclear weapons is legal in certain cases, such as cases of self-defense. Overall, the court said it could not find that there is an opinio juris in relation to nuclear weapons because there was such stark disagreement, meaning that nuclear war as a broad topic is not covered by customary international law. The International Law, Eighth Edition book echoed a similar sentiment, quoting from the ICJ: “There is in neither customary nor conventional international law any comprehensive and universal prohibition of the threat or use of nuclear weapons as such.”
That being said, many existing treaties regulate the usage of nuclear weapons, such as the following listed in the book: Limited Test Ban Treaty (1963), Threshold Test Ban Treaty (1974), Peaceful Nuclear Explosion Treaty (1976), Comprehensive Test Ban Treaty (1996) – not entered into force.
In addition to the existence of an opinio juris, the court went on to give an opinion on the legality of the use of nuclear weapons in the aforementioned case. The court concluded that it would have jurisdiction to comment on the legality of the use of nuclear weapons and thought to apply use of force laws to the question. The court specifically noted the fact that nuclear weapons cannot distinguish between civilian and military targets. Ultimately, the ICJ ruled that “[it] cannot conclude definitively whether the threat or use of nuclear weapons would be lawful or unlawful in an extreme circumstance of self-defense, in which the very survival of a State would be at stake.” The court additionally noted that NPT member states were obligated to “pursue in good faith and to conclude negotiations leading to nuclear disarmament in all its aspects under strict and effective international control.” Importantly, the ICJ was wary of the potential for its decision to tamper with nuclear deterrence and the delicate international balance.
Given these rulings, the ICJ has not made effective rulings regarding the NPT and would be unlikely to create any kind of enforceable ruling if nuclear violations were to occur, partially out of fear of impacting the deterrence balance that exists. It is far more likely that a treaty, such as the New START, be more effective at enforcing nuclear non-proliferation than the ICJ. But, in the case that the ICJ is called on to make a ruling regarding nuclear weapons, the UN Security Council would hypothetically be able to take action. The Security Council is able to take action to restore international peace in accordance with Chapter VII of the UN Charter and does so to enforce the ICJ’s rulings with recourse, such as establishing sanctions.
Other organizations, such as the World Health Organization (WHO), have also posed questions regarding the validity of nuclear weapon usage. In the case of the WHO, they asked whether nuclear weapons would breach their constitution due to the potential effects on health. The ICJ ruled once more in this case that they could not give an advisory opinion on this case because it left the scope of the WHO and encroached on the question of the general legality of the use of nuclear weapons. Additionally, the court stated that because the WHO was a specialized organization, this was exiting the organization’s “principle of specialty.”
Another potential method of mediation for nuclear disputes could be through general diplomatic efforts. This has been the most effective instrument of dispute resolution so far, simply given the fact that we have not yet experienced all-out nuclear warfare. Diplomacy is largely effective because of the stakes between nations when dealing with nuclear weapon negotiations. However, one of the prime locations for such diplomacy, the NPT Review Conference that occurs once every five years, proves a difficult environment to get things accomplished. The conference largely exists to hold the five nuclear weapon states that have signed the NPT accountable for fulfilling their treaty obligations. Likely because there is so much sensitivity regarding nuclear weapons, it is rare for a final outcome document to be adopted, even when the final document does not propose any dramatic changes. The Review Conference has not had an agreed outcome in over a decade, demonstrating its ineffectiveness as an arbitration mechanism.
Section Five: Policy Recommendations
In the coming weeks, it will be important to see what specifically Defense Secretary Hegseth comes up with during his “60-day” time period to create a more specific plan. The 60-day period expires at the end of March. It will be interesting to see whether the Trump
Administration’s plan will be at all feasible in regard to the technology and funding required, especially while the new Department of Government Efficiency (DOGE) is attempting to cut down on unnecessary costs. Nuclear and defense research is infamously expensive, but the DOGE likely will not target the defense budget, so this may not be a concern. Furthermore, the NPT has been indefinitely extended since 1995, but it will be fascinating to see if these changes in missile defense technology impact the conversation at the NPT Review Conference in 2026 or the negotiations of treaties such as the New START, which is also due for renewal next year. These details will most likely play a role in what any international dispute resolution body is able to do and what the reactions of other states will be.
Furthermore, I would remind U.S. policymakers that there is an extremely delicate balance that exists between nuclear weapon states, and a wrong move could be detrimental on a global scale. Although this discussion is not about expanding the U.S.’s nuclear arsenal, their current discussions could catalyze other states to do so, and it will be important for the U.S. to maintain strategic stability and prevent escalation, prioritizing values that are highlighted in international law.
For other states, I recommend that they begin to look towards potential solutions of international law, primarily through the aforementioned treaties, although it is unclear whether the Trump Administration would choose to listen to any solutions given by international courts, organizations, or treaties. Most importantly, even if the U.S. chooses to go through with the “Iron Dome for America,” I believe it is of the utmost consequence that other states do not begin violating their nuclear treaties and expanding their arsenals, as that will trigger extreme international issues and potentially a new era of nuclear arms races.
Featured/Headline Image Caption and Citation: A Medium Extended Air Defense System Missile is Launched, Image sourced from NARA & DVIDS Public Domain Archive | CC License, no changes made