Assassination in Tehran: Was Iranian Territorial Sovereignty Violated?

Ismail Haniyeh, head of the political office of Hamas, was killed at his residence in northern Tehran after attending the inauguration ceremony of Iran's new president.

The assassination raises critical questions under international law regarding the attack and the permissible responses by the Islamic Republic of Iran.

According to the Iranian government, Haniyeh was killed by a projectile fired at his residence around midnight.

As a guest of the Islamic Republic with a diplomatic passport, Haniyeh was granted immunity by Tehran authorities, making this act a violation of Iran's territorial integrity and the immunity accorded to Haniyeh.

While Israel has not officially claimed responsibility, the method and intent behind the assassination strongly suggest its involvement.

This incident occurred approximately nine months after the beginning of the conflict between Hamas and Israel.

The question arises whether Haniyeh was a legitimate military target.

Although Ismail Haniyeh was the head of the political office of Hamas and was not considered a military person in the definition of international law, he was one of the political leaders of the war between Hamas and Israel, having effective control over the militias involved with Israel.

Iranian officials, including the late Foreign Minister Hossein Amir-Abdollahian, engaged with Haniyeh in attempts to manage the conflict situation, underscoring his political and strategic significance.

Ali Khamenei, the leader of the Islamic Republic of Iran, had discussed issues related to the armed conflict between Israel and Hamas in meetings with Haniyeh at least twice after the start of the war.

This situation should have been clear to the Islamic Republic of Iran, which has been involved in direct exchanges of fire with Israel twice in the past five months.

The possibility that Israel considers Haniyeh a legitimate military target and might take action against him during his trip to Tehran should have been taken seriously.

Numerous operations attributed to Israel have been carried out in Iran in recent years, the most recent being in April of this year after the Islamic Revolutionary Guard Corps (IRGC) fired missiles at Israel.

It was reported that Israel responded to the IRGC's missile launch by targeting a location in Isfahan, though both Iranian and Israeli sides did not want to highlight this incident.

Haniyeh was killed in an operation attributed to Israel in Tehran. Undoubtedly, this act violates Iran's national sovereignty and territorial integrity, as prohibited by the United Nations Charter, which allows the victim government to take action under conditions that necessitate "legitimate defense."

The primary recommendation of the UN Charter is to refrain from military responses to military actions.

However, if the Islamic Republic initiates an operation under its interpretation of legitimate defense, international law does not entirely prohibit it.

Iran's interpretation of legitimate defense is relatively new in the context of the UN Charter. Similar to the United States' interpretation, Iran considers it a "military deterrent" against repeated attacks.

Using this interpretation, the Islamic Republic launched missiles directly from Tehran toward Israel after the attack on its consulate in Damascus, which resulted in the death of several senior commanders of the IRGC and its Quds Force, the overseas branch.

From a military perspective, it seems that the missile launch, which was accompanied by suicide drones, did not achieve the desired deterrence for the Iranian government.

This time, Israel directly targeted an official guest of the Islamic Republic of Iran, killing him in Tehran.

Israeli Prime Minister Benjamin Netanyahu stated after Haniyeh's assassination in Tehran—which occurred hours after the assassination of Fuad Shukr, a military leader of Lebanon's Hezbollah and the designer of the attack on American marines in Beirut in the early 1980s—that Israel has dealt significant blows to Iran's proxy forces, including Hamas and Hezbollah, over the past few days.

These statements effectively acknowledge responsibility for Haniyeh's assassination in Tehran.

The Iranian government, in its official statements and through Ali Khamenei's speeches, has promised revenge, which, if carried out, could bring the two countries closer to an all-out war.

In the past decade, Iran and Israel have engaged in a combination of proxy and direct warfare, which led to a limited direct conflict for the first time this spring.

However, the two countries have not yet entered into a war or military battle in the classical and legal sense.

Any Iranian military response to the assassination of Haniyeh in Tehran could escalate the current conflict to a new level, potentially leading to a full-scale military confrontation between the two sides.