President Donald Trump has been told to "never threaten an Iranian" after starting a potentially dangerous social media stand-off by warning Iran not to threaten America again, or it will face its "official end".
The US leader tweeted on Monday: “If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again!”
His tweet received a swift response from the foreign minister of Iran, Javad Zarif, who said Trump "hopes to achieve what Alexander, Genghis & other aggressors failed to do".
He added: "Iranians have stood tall for millennia while aggressors all gone. #EconomicTerrorism & genocidal taunts won't "end Iran".
"#NeverThreatenAnIranian. Try respect—it works!"
The Twitter spat came amid heightened tensions between America and Iran following Mr Trump’s decision a year ago to pull America out of Tehran’s nuclear deal with world powers.
Semi-official news agencies in Iran then reported its production of low-enriched uranium had quadrupled.
A quadrupling of production would mean Iran will likely go beyond the stockpile limitations set by the 2015 nuclear deal with world powers.
Iran says it has informed the International Atomic Energy Agency, the UN nuclear watchdog, of its decision but the IAEA did not immediately respond to a request for comment.
Mr Trump’s tweet came after he seemingly sought to soften his tone on Iran following days of heightened tension sparked by a sudden deployment of bombers and an aircraft carrier to the Persian Gulf over still-unspecified threats.
In the time since, officials in the United Arab Emirates alleged four oil tankers have been sabotaged.
Yemeni rebels allied with Iran launched a drone attack on an oil pipeline in Saudi Arabia.
US diplomats also relayed a warning that commercial airlines could be misidentified by Iran and attacked, something dismissed by Tehran.
While both Washington and Tehran say they do not seek war, many worry that any miscalculation at this moment could spiral out of control.
Iraqi military spokesman Brigadier General Yahya Rasoul said the rocket that landed near the US embassy was believed to have been fired from east Baghdad, an area home to Iranian-backed Shia militias.
Mr Trump campaigned on pulling the US from the 2015 nuclear accord, which saw Iran agree to limit its enrichment of uranium in exchange for the lifting of economic sanctions.
Since the withdrawal, the US has re-imposed previous sanctions and come up with new ones, as well as warning nations around the world they would also be subject to sanctions if they import Iranian oil.
Iran has announced it will begin backing away from the terms of the deal, setting a 60-day deadline for Europe to come up with new terms or it will begin enriching uranium closer to weapons-grade levels.
Tehran long has insisted it does not seek nuclear weapons, though the West fears its programme could allow it to build atomic bombs.
In an interview aired on the Fox News Channel, Mr Trump called the nuclear deal a “horror show”.
“I just don’t want them to have nuclear weapons and they can’t be threatening us,” Mr Trump said.
However, the nuclear deal had kept Iran from being able to acquire enough highly enriched uranium for a bomb.
UN inspectors repeatedly certified that Iran was in compliance with the accord.
Meanwhile, the US Navy’s 5th Fleet has announced it will begin “enhanced security patrols” in international waters with members of the Gulf Cooperation Council, which includes Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates.
Already, the USS Abraham Lincoln aircraft carrier, the amphibious assault ship USS Kearsarge and others are in the Arabian Sea, close to the Strait of Hormuz, the narrow mouth of the Persian Gulf through which a third of all oil traded at sea passes.