EDITOR’S CORNER: When Does Regime Change Cross Legal Lines?

We were struck by another shocking development over the weekend when the United States launched a major military operation against Iran early Saturday morning. The strikes included extensive air and missile attacks across multiple targets in the country. In the initial assaults, Iran’s Supreme Leader, Ayatollah Ali Khamenei, was reportedly killed along with a number of senior Iranian officials, including top military leaders such as the defense minister and commanders of the Revolutionary Guard.

In this blog post, I want to briefly explore what this attack on Iran means, how it might escalate, and the legal questions surrounding it. This is not without precedent — even in Venezuela, there have been U.S.-led strikes against the Maduro regime that were carried out without consultation. Former President Trump did not seek approval from Congress, the United Nations, or allied nations in those actions.

WHAT HAPPENED IN IRAN?

First, let's discuss what happened in Iran over the weekend. The United States and Israel launched a major coordinated military offensive against Iran, beginning early Saturday morning. The strikes involved extensive air and missile attacks on strategic military and leadership targets across the country. Iranian state media and international reporting indicate that Supreme Leader Ayatollah Ali Khamenei, who had led the Islamic Republic since 1989, was killed in the initial barrage, along with several senior officials and advisors. The assault reportedly targeted his compound in Tehran and other key command centers, marking one of the most significant direct actions against Iran’s leadership in decades.

The impact of these strikes immediately triggered widespread fear and uncertainty within Iran, with explosions reported in major cities and emergency measures such as school closures and evacuations. The government announced a period of national mourning while also mobilizing retaliatory missile and drone responses against U.S. and Israeli positions in the region. 

The death of Khamenei has created a leadership vacuum and intensified speculation about succession, as interim political and religious bodies begin the process of determining who will assume the country’s highest authority.

WHAT IS WAS THE INTERNATIONAL REACTION?

The international reaction was swift and deeply divided. The United Nations called for restraint and warned of the risk of a broader regional war. The European Union expressed grave concern and appealed for immediate de-escalation, while leaders in Russia and China condemned the strikes as violations of international law and state sovereignty. NATO members held consultations amid fears of retaliatory attacks and wider instability across the Middle East. Global markets reacted nervously, and governments around the world began reviewing security measures for their embassies and military personnel in the region.

Some leaders described the strikes as unlawful and urged both sides to avoid further escalation. Iran responded with missile and drone attacks targeting U.S. and allied military assets across the region. Reports indicate that some strikes affected locations in Gulf states and near Western military facilities, heightening regional tensions. Russia strongly criticized the killing of the Ayatollah but did not take direct military action, instead calling for de-escalation and diplomatic engagement.

WHAT'S NEXT?

This is an extraordinarily uncertain moment, and much depends on what happens next. Iran is in the process of selecting a new Supreme Leader, yet its leadership structure appears increasingly fragile amid ongoing strikes and targeted killings. At the same time, there is no clearly articulated transition framework publicly outlined by the United States following the killing of Iran’s highest authority. Compounding this instability, Iran has shown no indication that it intends to de-escalate. Its rhetoric and actions signal a determination to retaliate, raising the risk of sustained or widening conflict.

Beyond the immediate military dimension, there are serious implications for the international order. If states begin to justify military action primarily on the basis of opposition to another country’s regime, that could set a far-reaching and destabilizing precedent. Similar reasoning could be invoked elsewhere — for example, by China in relation to Taiwan, or by Russia in disputes involving European neighbors. The erosion of norms surrounding sovereignty and non-intervention could embolden major powers to act more aggressively, weakening already strained global governance structures.

There is also the possibility that the conflict could expand across the Middle East. A direct strike on Türkiye, for instance, would carry enormous consequences. As a NATO member, Türkiye falls under Article 5 of the alliance treaty, meaning an attack on one member is considered an attack on all. Such a scenario would test alliance cohesion and raise profound questions about collective defense commitments. Beyond interstate escalation, the risk of increased terrorist attacks globally cannot be dismissed, particularly if militant groups seek retaliation. A large-scale refugee crisis is another serious concern. Iran’s population of roughly 90 million far exceeds that of Syria, whose civil war beginning in 2015 severely strained Europe during the refugee crisis. Instability or failed regime change in Iran could generate displacement on an even larger scale.

Amid rising great-power tensions, there is also a longer-term proliferation risk. Some smaller states may conclude that an independent nuclear deterrent is the only reliable safeguard against coercion by stronger powers, including the United States. Wealthier Gulf countries — and potentially even certain European states — could begin reassessing whether developing their own nuclear arsenals is necessary for long-term security. For countries with established civilian nuclear energy programs, the technical foundation for such a capability already exists, potentially lowering the barriers to pursuing it should a political decision be made.

CONCLUSION

In conclusion, the situation in Iran highlights growing global instability and uncertainty about the future of international law, sovereignty, and military conflict. The possibility of further escalation remains a major concern for global security and economic stability.

At the same time, the conflict could expand regionally and increase risks such as terrorism and refugee displacement. How world leaders respond will be critical in determining whether tensions continue to rise or begin to de-escalate.