Donald Trump's warning Iran's President not to threaten the United States again, otherwise they'll "suffer consequences".
It's after Iranian President Hassan Rouhani cautioned the US President against pursuing hostile policies towards Tehran.
In comments quoted by the ISNA news agency, the Iranian leader said his country will respond to 'threat with threat'.
He said: "Iran's power is deterrent and we have no fight or war with anybody but the enemies must understand well that war with Iran is the mother of all wars and peace with Iran is the mother of all peace."
He added: "Mr. Trump! We are the people of dignity and guarantor of security of the waterway of the region throughout the history. Don't play with the lion's tail; you will regret it".
Late on Sunday night, Mr Trump tweeted that America's not a country which will stand for "demented words of violence and death".
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