President Donald Trump on Sunday hit back at bellicose comments by Iran's president, warning him of dire consequences as the US intensifies its campaign against the Islamic republic.
"NEVER, EVER THREATEN THE UNITED STATES AGAIN OR YOU WILL SUFFER CONSEQUENCES THE LIKES OF WHICH FEW THROUGHOUT HISTORY HAVE EVER SUFFERED BEFORE," Trump said on Twitter in a direct message to President Hassan Rouhani.
Earlier Sunday the Iranian leader had warned Trump not to "play with the lion's tail," saying that conflict with Iran would be the "mother of all wars".
The US president, writing his entire message in capital letters, continued his riposte:
"WE ARE NO LONGER A COUNTRY THAT WILL STAND FOR YOUR DEMENTED WORDS OF VIOLENCE & DEATH. BE CAUTIOUS!"
His comments Sunday night came after Secretary of State Mike Pompeo, in a major address to the Iranian diaspora in California, said Washington is not afraid to sanction top-ranking leaders of the "nightmare" Iranian regime.
Trump in May pulled the US out of a hard-won agreement with Tehran, also signed by Britain, China, France, Germany and Russia, which lifted sanctions in exchange for curbs on Iran's nuclear program.
The 2015 agreement was in response to fears that Iran was developing a nuclear bomb.
European allies maintain their support for the deal and have vowed to stay in it, though their businesses fear US penalties.
Following Washington's pullout Pompeo unveiled Washington's tougher line under which, he said, the US would lift the new sanctions if Iran ended its ballistic missile program and interventions in regional conflicts from Yemen to Syria.
Rouhani immediately dismissed those US threats and on Sunday said: "You cannot provoke the Iranian people against their own security and interests."
- 'More to come' -
In a televised speech ahead of Pompeo's address, Rouhani repeated his warning that Iran could shut down the strategic Strait of Hormuz, a vital shipping lane for international oil supplies.
"Peace with Iran would be the mother of all peace and war with Iran would be the mother of all wars," Rouhani said.
On Saturday, Iran's supreme leader Ayatollah Ali Khamenei said US words and "even... their signature" cannot be trusted, "so negotiations with the United States are useless."
The US in January had already sanctioned Sadeq Larijani, the head of Iran's judiciary, for human rights violations, Pompeo noted on Sunday.
"We weren't afraid to tackle the regime at its highest level," he said, confirming that Washington wants all countries to reduce their imports of Iranian oil "as close to zero as possible" by November 4, or face American sanctions.
Pompeo called on "all governments to end their flirtations" with Iran's regime, and said "there's more to come" in terms of sanctions.
"Regime leaders -- especially those at the top of the IRGC and the Quds Force like Qasem Soleimani -- must be made to feel painful consequences of their bad decision making," said Pompeo, a longtime Iran hawk. He was referring to Iran's special forces and Revolutionary Guards.
Roundly applauded by his audience, Pompeo affirmed support by Washington for protesters who have taken to the streets of Iran as economic woes mount after the US withdrawal from the nuclear accord.
"The regime in Iran has been a nightmare for the Iranian people," he said.
"The United States hears you. The United States supports you. The United States is with you."
To reinforce that message, Washington's top diplomat announced an intensified American propaganda campaign, through the launch of a multimedia channel with 24-hour coverage on television, radio, and social media.
Pompeo refused to distinguish between moderates and radicals at the heart of the Islamic republic.
The Trump administration is regularly suspected of favoring regime change in Iran, and Pompeo said "our hope is that ultimately the regime will make meaningful changes in its behavior both inside Iran and globally."