US President Donald Trump has launched a blistering all-capitals attack on Iran via Twitter.

In a vicious response to Iranian President Hassan Rouhani, the US leader warned him to "NEVER, EVER THREATEN THE UNITED STATES AGAIN", or he will "SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE".

To Iranian President Rouhani: NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE. WE ARE NO LONGER A COUNTRY THAT WILL STAND FOR YOUR DEMENTED WORDS OF VIOLENCE & DEATH. BE CAUTIOUS!

— Donald J. Trump (@realDonaldTrump) July 23, 2018

It came after Rouhani issued a warning to Trump, which was disseminated via the country's state media network.

WHAT WAS THE THREAT?

President Rouhani threatened Mr Trump earlier today, warning that the "mother of all wars" would take place if the US maintained its hostilities.

"Mr Trump, don't play with the lion's tail, this would only lead to regret," he told a gathering of Iranian diplomats.

"America should know that peace with Iran is the mother of all peace, and war with Iran is the mother of all wars.

"You are not in a position to incite the Iranian nation against Iran's security and interests."

WHAT WAS THE THREAT?

President Rouhani threatened Mr Trump earlier today, warning that the "mother of all wars" would take place if the US maintained its hostilities.

"Mr Trump, don't play with the lion's tail, this would only lead to regret," he told a gathering of Iranian diplomats.

"America should know that peace with Iran is the mother of all peace, and war with Iran is the mother of all wars.

"You are not in a position to incite the Iranian nation against Iran's security and interests."