Examining Israel’s aggression against Iran from the perspective of international criminal law

On June 13, 2025, Israel launched a military aggression against Iran, targeting various locations in what is considered a clear act of aggression.

During this assault, Israeli strikes targeted Iranian facilities, scientists, and military commanders. In the course of the 12-day conflict, multiple attacks were also carried out against civilian targets.

According to available figures, these attacks killed more than 1,000 people and injured several thousand others.

Since the start of this aggression, many legal scholars have analyzed the matter from different angles of international law, particularly the jus ad bellum (right to war). However, it has received less attention from the perspective of international criminal law.

Does Israel’s action constitute the crime of aggression?

Under international law, aggression is classified as an international crime. While it stems from the broader prohibition on the use of force under Article 2(4) of the UN Charter, aggression is a crime with specific legal elements.

The Opinio Juris platform wrote that determining whether Israel’s attack on Iran constitutes the crime of aggression requires analyzing two issues:

1.     Whether the attack involved the use of force in violation of Article 2(4) of the UN Charter.

2.     Whether that use of force gives rise to individual criminal responsibility.

The platform continued: As most scholars agree, Israel’s attack on Iran is a clear violation of Article 2(4). The next question is whether it constitutes the crime of aggression. It is important to note that the crime of aggression under the Rome Statute is broader than its counterpart under customary international law.

The Rome Statute’s definition is straightforward:

• A criminal act of aggression is an act of aggression which, by its character, gravity, and scale, constitutes a manifest violation of the UN Charter.
• An act of aggression is any act that violates Article 2(4) of the UN Charter.

The customary law definition is narrower, though its precise scope is debated. Possible definitions include:

• An act aimed at annexing territory or subjugating the victim state.
• An act intended to acquire territory, seize assets, or alter the foreign policy of the victim state.
• An act aimed at changing the political status quo of the victim state by attacking its military, governmental, or economic institutions.
• An act intended to establish a military occupation of the victim state.

Israel’s attack on Iran meets the definition of a criminal act of aggression under both frameworks. Under customary law, it likely satisfies several of the above criteria.

Opinio Juris added that under the Rome Statute, since any violation of Article 2(4) is considered an act of aggression, the only question is whether this invasion, in terms of character, gravity, and scale, constitutes a manifest violation of Article 2(4).

Although the “manifest violation” threshold is inherently vague, there is no doubt that Israel’s attack was of significant gravity and was carried out across a substantial portion of Iranian territory.

The invasion of another state’s territory was clearly unlawful under the UN Charter and represented a very serious breach of it.

The platform stressed that all three criteria—character, gravity, and scale—appear to have been met. Moreover, it could be strongly argued that meeting even two of the three would be sufficient for an international court to conclude that the use of force constituted a manifest violation of the UN Charter.