TEMPO.CO, Jakarta - UN Secretary General Antonio Guterres has condemned the ongoing offensive against Iran launched by the United States and Israel on February 28. He cited the UN Charter's ban on the use of force against another country and said the attacks were "a grave threat to international peace and security."
"I think that most international lawyers would agree that there is no legal justification for this. It's in violation of the UN Charter," Gissou Nia, a human rights lawyer and director of the Strategic Litigation Project at the Atlantic Council, told DW. "We're dealing with an attack on Iran that obviously is not legal under international law nor the US's own laws on how you go to war."
However, Nia added, the international legal system had also failed to "bring redress to the 92 million Iranians, many of whom have suffered international law violations and atrocity crimes committed against them by the Iranian regime over 47 years."
It is not the first time that the legality of military operations carried out by the US has been questioned. In contrast to past wars such as the 2003 invasion of Iraq, this time the US government appears uninterested in persuading the world that it is acting in accordance with international law. "I don't need international law," Trump said in an interview with the New York Times on January 7, 2026, adding: "I'm not looking to hurt people."
Can the US and Israel claim self defense to justify their attack?
US and Israeli officials have argued that they were acting against Iranian threats, particularly the danger of Iran producing and using a nuclear weapon. But legal experts say it's unclear whether those threats were immediate enough to meet the UN's strict rules on self defense.
Under Article 51 of the UN Charter, a state may use force in self defense only after an armed attack. A broader reading of international law also allows force against an "imminent threat," though this interpretation is highly contested.
Iranian government officials have repeatedly threatened to "destroy" Israel. But experts note that hostile rhetoric alone does not make preemptive force lawful.
During the military buildup, top US officials had warned about Iran's nuclear capabilities, with envoy Steve Witkoff saying on February 21 that Iran was "probably a week away" from producing industrialgrade bombmaking material.
This, however, appears to contradict statements US President Donald Trump made after the 2025 bombing of Iran. At the time, he said Iran's nuclear facilities had been obliterated.
Was the killing of Khamenei an illegal assassination?
Under international law, killing an enemy's head of state is highly controversial: while combatants can be targeted in wartime, the intentional killing of political leaders is viewed as assassination, especially if the attack itself was not justified under the UN Charter. This makes Khamenei's death in joint US-Israeli strikes one of the most legally sensitive actions of the conflict so far.
Gissou Nia said "at the same time, it did result in the killing of the former supreme leader of Iran, who is responsible for hundreds of thousands of deaths of Iranians over the years. And notably, a massacre on January 8 and 9 of this year, which was one of the worst single-day massacres in contemporary history. So in that sense, many of the Iranian people are grateful. Some of them are also communicating that they wished they could have seen the supreme leader in a court. They would have wanted to see him answer for his crimes. So it's very complicated."
What about US laws prohibiting assassinations?
The US also has a ban on American involvement in assassinations. This ban was set out in an executive order first signed by President Gerald Ford in 1976 and later amended by other presidents. It states that "no person employed by or acting on behalf of the United States Government shall engage in or conspire to engage in assassination."
Yet, over the past decades, the United States has gradually eroded this prohibition. "The line was very thin to start with," said Luca Trenta, associate professor of international relations at Swansea University in the UK. "The US had adopted a policy that actions taken in self-defense would not violate the ban." He told DW that the killing of a foreign leader via targeting command-and-control infrastructures or compounds was no longer regarded as assassination, mentioning the US airstrike that failed to kill Libyan leader Muammar Gaddafi in 1986. "I think the difference here is that the US government and Trump, via social media, are taking full credit for this assassination."
Was Iran allowed to strike back at Israel and US bases?
Iran launched missiles and drones at Israel as well as at US bases and other targets across the Gulf shortly after the strikes began. Tehran argues it is responding to US and Israeli military bases in self defense after having been attacked. Under international law, a state that suffers an armed attack may respond in self defense. But the strikes on civilian sites, for example in Israel and Dubai, highlight clear legal limits: targeting civilians is banned under international humanitarian law, and attacking states not involved in the conflict is also prohibited.
Analysts describe some of Iran's actions as "misdirected selfdefense," particularly where strikes extended to the territory of third countries hosting US forces rather than solely against the attacking states themselves. Strikes with missiles or drones presumably originating from Iran have been reported from several countries in the region, including Bahrain, Qatar, the UAE, Israel, the Palestinian Territories, Kuwait, Jordan, Saudi Arabia, Oman, and Cyprus.
What do US allies say?
US allies in Europe have reacted cautiously. Many governments avoided directly criticizing the US and Israel, even as they expressed concern about a wider regional war. European leaders largely condemned Iran's retaliation while staying silent on the legality of the initial USIsraeli strikes.
German Chancellor Friedrich Merz said on Sunday that "existing rules, including those of international law, are being observed less and less." But, he added, now was "not the time to lecture our partners and allies." In recent decades, repeated attempts had been made to influence Iran through measures grounded in international law. This had "obviously had no effect." German Foreign Minister Johann Wadephul said on Monday on Deutschlandfunk radio that there were "significant questions" and "doubts" regarding the classification under international law. At the same time, he referred to the threat posed by Iran.
European Commission President Ursula von der Leyen called the developments in Iran "greatly concerning" and stressed the need to protect civilians and respect international law.
Beyond Europe, reactions have been mixed. Close partners such as Australia and Canada expressed support for the US, while others kept their distance. Russia and China, meanwhile, criticized the USIsraeli operation. The Russian government, responsible for the full-scale invasion of neighboring country Ukraine, stated: "Russia, as always, stands ready to assist in advancing peaceful solutions grounded in international law."
Is this war another sign that international law is weakening?
Experts warn that the conflict could be a turning point. As powerful states rely more on unilateral strikes and broad claims of self defense, the rules meant to prevent war may be eroding. Political scientist Luca Trenta told DW: "I think we are seeing the emergence of a ruthless form of foreign interventions without any particular concern for domestic or international legal constraints."
He said that so far the Trump administration, when it has conducted military strikes or operations, has not shown a particularly keen interest in justifying its conduct via the standards of international law. "This could be seen in the case of Nicolas Maduro, who was apprehended in Venezuela," he said. "The justification that did emerge almost entirely disregarded international law and spoke only in terms of US domestic law."
Trenta said that he was especially concerned that the world was witnessing an escalation of assassination in international politics. Other states might also take notice, and assassination might become more prominent overall."
Read: Iran War Unjustifiable Under International Law, Says PKB Politician
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