Iranian Parliament Speaker Ali Larijani said Sunday the killing of senior military commander Qasem Soleimani in a U.S. airstrike was an "outright violation" of the United Nations Charter.
"U.S. President [Donald Trump]'s brutal act is a war crime," he said in an address to parliament cited by the official IRNA news agency.
Larijani said Soleimani's killing has changed the political balance of both the region and the international community.
Soleimani, the head of Iran's Revolutionary Guards' elite Quds force, was killed in a U.S. drone airstrike in Iraq on Friday.
His death marked a dramatic escalation in tensions between the U.S. and Iran, which have often been at a fever pitch since Trump chose in 2018 to unilaterally withdraw Washington from a 2015 nuclear pact world powers struck with Tehran.
Iranian Supreme Leader Ali Khamenei, who gave Soleimani the country's highest honor last year, vowed "severe retaliation" in response to his killing.
The Pentagon accused Soleimani of plotting the embassy attack and planning to carry out additional attacks on U.S. diplomats and service members in Iraq and the region.
