Iran’s newly declared Supreme Leader, Alireza Arafa, has vowed retaliation against the United States and Israel following recent airstrikes Tehran described as an unprovoked attack on its territory.

In a statement released Tuesday on social media, Arafa said diplomatic efforts had ended and accused Washington of crossing a “red line.”

“The time for negotiations is over. The United States has chosen to cross the red line, the line of irreparable harm,” he said. “By launching this war, they have signed their own death warrant.”

His remarks come days after coordinated U.S. and Israeli strikes reportedly targeted Iranian military installations and strategic infrastructure, sharply escalating tensions among Tehran, Washington and Tel Aviv.

Iranian authorities have described the strikes as unjustified and denied allegations that they were preparing imminent hostilities. U.S. officials have long accused Tehran of backing armed proxy groups across the Middle East and pursuing destabilising missile and nuclear programmes — claims Iran has consistently rejected.

Arafa dismissed Western assertions that the strikes were pre-emptive measures against a nuclear threat. “They brandish the nuclear specter like a scarecrow,” he said, warning that Iran was prepared to respond.

He also issued a direct warning to Israel, saying the country would face consequences for its actions. The rhetoric has heightened fears of a broader regional confrontation that could draw in armed groups aligned with Tehran in Lebanon, Syria, Iraq and Yemen.

Analysts say any sustained conflict risks disrupting global energy markets and further destabilising an already volatile region, as diplomatic efforts to contain the crisis appear to have stalled.