US president Donald Trump has warned Iran not to threaten America again, or it will face its “official end”.
Trump tweeted the warning shortly after a rocket landed near the US embassy in Baghdad.
Relations between the US and Iran have been worsening since Mr Trump’s decision a year ago to pull America out of Tehran’s nuclear deal with world powers.
The US leader tweeted: “If Iran wants to fight, that will be the official end of Iran. Never threaten the United States again!”
White House officials did not elaborated on the tweet, but the message came after a rocket landed less than a mile from the sprawling US embassy in Baghdad in the Iraqi capital’s heavily fortified Green Zone on Sunday night.
No group immediately claimed responsibility for the rocket launch.
Iran’s foreign minister responded with a tweet of his own in English. Mohammad Javad Zarif posted his own message on Twitter, saying Mr Trump had been “goaded” into “genocidal taunts”.
Mr Zarif wrote that Mr Trump “hopes to achieve what Alexander (the Great), Genghis (Khan) & other aggressors failed to do.”
He added: “Iranians have stood tall for a millennia while aggressors all gone.”
He ended his tweet with #neverthreatenaniranian and: “Try respect - it works!”
Trump had seemingly softened 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 also launched a drone attack on an oil pipeline in Saudi Arabia.
And US diplomats 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.
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, including Bahrain, Kuwait, Oman, Qatar, Saudi Arabia and the United Arab Emirates.
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.