A senior Iranian security official has warned that Tehran will treat any nation's participation in or backing of the United States' sweeping anti-Iran economic campaign as an 'act of war' — a sharp escalation in rhetoric that follows US President Donald Trump's announcement of what he called the most punishing economic operation ever launched against any country.

What Rezaei Said

Mohsen Rezaei, secretary of Iran's Supreme National Security Council, issued the warning in a social media post, stating: 'If the economic war continues, not a single drop of oil will be exported, neither through the Strait of Hormuz nor from anywhere in the Persian Gulf. Iran will regard any country's participation in or support for America's economic war against the Iranian people as an act of war.'

Rezaei had earlier made similar remarks in an interview with state-run IRIB TV on Saturday, warning that Tehran would first seek to negotiate with any country drawn into the conflict, but would 'strike their interests' if they refused to stay out. He specifically cautioned that surrounding nations joining a US-led siege would trigger a full closure of the Strait of Hormuz — a critical global oil transit chokepoint.

Trump's 'Economic D-Day' Declaration

The Iranian response came directly after Trump posted on Truth Social on Wednesday, announcing 'the most crushing economic operation ever taken' against any country that provides a financial lifeline to Iran. Trump described the move as 'Economic Warfare and Isolation on an unprecedented scale,' branding it an 'ECONOMIC D-DAY.'

The declaration represented a significant hardening of the US position and appeared to target third-party nations — including potential trade partners of Iran — with the threat of secondary economic consequences.

The Hormuz Threat and Oil Leverage

Rezaei's warning about the Strait of Hormuz carries significant weight: roughly 20% of global oil trade transits the waterway daily. A closure, even a partial or temporary one, would send energy prices sharply higher and disrupt supply chains across Asia, Europe, and beyond.

Rezaei also noted that Iran has developed extensive mechanisms over the years to circumvent US sanctions and sustain oil exports — signalling that Tehran does not see itself as economically defenceless even under maximum pressure. He added that the Hormuz Strait would remain closed unless Washington fulfils its commitments under the Iran-US peace memorandum of understanding signed in June, insisting that the US must act first.

The June MoU and Stalled Talks

On 18 June, the United States and Iran signed a memorandum of understanding aimed at ending hostilities across the region, including in Lebanon. Under the MoU, both sides were to hold negotiations within 60 days — a window that closed on Monday — with the goal of reaching a final agreement.

The fate of those talks remains unclear following a fresh escalation between the two countries last month. The current exchange of threats suggests the diplomatic track is under severe strain, with both sides hardening their positions publicly before any resumed dialogue.

What Comes Next

The standoff now hinges on whether third-party nations — particularly major importers of Iranian oil such as China and India — will respond to US pressure or risk being labelled hostile by Tehran. Both the economic and security dimensions of this crisis are likely to intensify in the coming days as the 60-day MoU deadline passes without a final agreement in place.