By Michelle Nichols
Iran told the UN Security Council and Secretary-General Antonio Guterres on Friday local time it reserves the right to self-defence under international law after the United States killed its most prominent military commander Qassem Soleimani.
In a letter, Iranian UN Ambassador Majid Takht Ravanchi said the killing of Soleimani "is an obvious example of state terrorism and, as a criminal act, constitutes a gross violation of the fundamental principles of international law, including, in particular ... the Charter of the United Nations."
Soleimani, a 62-year-old general who headed the overseas arm of Iran's Revolutionary Guards, was regarded as the country's second most powerful figure after Supreme Leader Ayatollah Ali Khamenei.
The US killed Soleimani in an overnight attack in Iraq authorised by President Donald Trump. A senior Trump administration official said Soleimani had been planning imminent attacks on US personnel in the Middle East.
The US could seek to justify killing Soleimani under Article 51 of the UN Charter, which covers an individual or collective right to self-defence against armed attack.
Under Article 51, countries are required to "immediately report" to the 15-member Security Council any measures taken in exercising the right of self-defence. The US used Article 51 to justify taking action in Syria against Islamic State militants in 2014.
Diplomats said no such letter had yet been received from Washington on the killing of Soleimani.
Guterres was deeply concerned by the recent rise in tensions in the Middle East, his spokesman, Farhan Haq, said in a statement earlier on Friday.
"This is a moment in which leaders must exercise maximum restraint. The world cannot afford another war in the Gulf," Haq said.
Meanwhile, an air strike has hit two cars carrying Iran-backed militia north of Baghdad, one day after the US attack that killed Soleimani, an Iraqi official says.
The official said five members of the militia were killed in the latest strike.